Donald Trump has threatened to withhold £700m of investment in Scotland if he is banned from entering the UK.
MPs will debate later this month whether the US presidential hopeful should be refused entry.
It follows the billionaire property tycoon calling for a temporary ban on Muslims entering the US.
More than half a million people backed a petition calling on the tycoon to be barred for his comments, triggering a debate in the Commons.
However, there will be no vote at the end of the debate and it will be up to Home Secretary Theresa May to decide whether or not Mr Trump should be excluded from the UK.
Mr Trump owns the Turnberry golf course in South Ayrshire as well as Trump International Golf Links near Aberdeen.
In a statement, his Trump Organisation said it had planned to invest more than £200m at Turnberry and a further £500m at the Aberdeenshire course.
But it warned that any action to restrict travel would force it to "immediately end these and all future investments we are currently contemplating in the United Kingdom".
Image copyrightReutersImage captionMr Trump bought the Turnberry course last year for about £35m
It added: "Westminster would create a dangerous precedent and send a terrible message to the world that the United Kingdom opposes free speech and has no interest in attracting inward investment.
"This would also alienate the many millions of United States citizens who wholeheartedly support Mr Trump and have made him the forerunner by far in the 2016 presidential election.
"Many people now agree with Mr Trump that there is a serious problem that must be resolved. This can only be achieved if we are willing discuss these tough issues openly and honestly."
Prime Minister David Cameron has previously labelled Mr Trump's comments "stupid" but said he did not support a ban, telling MPs the tycoon would "unite us all against him" if he visited the UK.
In the report by Germany's national police, seen by Spiegel and Bild newspapers, an unidentified senior officer describes the scene in Cologne on New Year's Eve as "chaotic and shameful".
It recounts how police were met by "anxious citizens with crying and shocked children" when they arrived at the city's main railway station.
"On the square outside were several thousand men, most of a migrant background, who were firing all kinds of fireworks and throwing bottles into the crowd at random."
German media, also quoting internal police reports, say that significant numbers of Syrian, Afghan and Iraqi migrants were in the crowd - although it is unclear if any were involved in the attacks.
What we know of the New Year's Eve attacks
Image copyrightReutersImage captionPolice say the situation outside the station was out of control
Scores of women say they were sexually assaulted and had mobile phones and bags stolen by large groups of men during New Year celebrations in the centre of Cologne
As many as 1,000 men - described as drunk and aggressive and many of North African and Arab appearance - were reported to have been behind the attacks
Cologne police say they have received 121 criminal complaints - at least three-quarters of those were of sexual assault, including two alleged rapes
Sixteen suspects have been identified but no-one has yet been arrested, police say
Similar attacks were reported in Hamburg, where 30 complaints were filed, and in Stuttgart
Officers managed to clear the square, but the chaos continued with shocked and crying women reporting large numbers of sexual assaults.
"The task forces could not cope with all the events, assaults, and crimes - there were just too many happening at the same time," the senior officer concluded in the national police report.
Cologne police chief Wolfgang Albers has rejected claims teams were understaffed, insisting "we were well prepared".
But he described what happened as "a completely new dimension of crime".
Media captionA woman tells the BBC's Jenny Hill how she and her friends became surrounded
An initial police assessment - describing a "relaxed atmosphere" in the city on New Year's Eve - was later dismissed as inaccurate.
Correspondents say the identification of the attackers as North African or Arab in appearance has caused alarm in Germany because of the influx of more than a million migrants and refugees in the past year.
Speaking in Berlin on Thursday, German Chancellor Angela Merkel said Germany needed to examine whether it had done enough to deport foreigners who committed crimes.
"What happened on New Year is not acceptable. These are repugnant criminal acts that a state, that Germany will not accept.
"We must examine again and again whether we have already done what is necessary in terms of deportations from Germany, in order to send clear signals to those who are not prepared to abide by our legal order."
"I feel so ashamed" - Anger on Arab-language social media
Facebook user Israa Ragab: "Every time I watch the TV and hear them saying the suspects could be from North Africa or Arabs I feel so ashamed and disgusted"
Deutsche Welle Arabic journalist Nahla Elhenawy: "The ugliness of our region is reaching Germany"
@Farcry99 on Twitter: "Will Europe regret receiving people who suffer from religious and political repression?"
As well as the attacks in Cologne, women were targeted in Hamburg and Stuttgart.
In Duesseldorf, 40km (25 miles) to the north of Cologne, police have been investigating claims that gangs of men from North Africa have been robbing their victims by deliberate body contact.
They are examining whether there is a link to similar claims in Cologne.
Earlier Ralf Jaeger, interior minister for North Rhine-Westphalia, said police had to "adjust" to the fact that groups of men had attacked women en masse.
He also warned that anti-immigrant groups were trying to use the attacks to stir up hatred against refugees.
"What happens on right-wing platforms and in chatrooms is at least as awful as the acts of those assaulting the women," he said. "This is poisoning the climate of our society."
The "anti-Islamisation" Pegida movement and the right-wing AfD have said the attacks were a consequence of large-scale migration.
But Cologne's mayor said there was no reason to believe those behind the attacks were refugees.
Public broadcaster ZDF has apologised on social media because it failed to report on the mass assaults on its Monday evening news bulletin, after the news began to emerge.
The suspect was carrying a meat cleaver and wearing a dummy suicide vest.
A piece of paper found on his body "pledged allegiance" to so-called Islamic State and vowed revenge for French "attacks in Syria", AFP reported.
Officials have named him as a convicted thief, Sallah Ali, born in Morocco.
Minutes before he was shot, President Francois Hollande had praised police in a speech on last year's killings.
Gunmen murdered 17 people in attacks, including at Charlie Hebdo magazine and a Jewish supermarket.
In his address, Mr Hollande said 5,000 extra police and gendarmes would be added to existing forces by 2017 in an "unprecedented" strengthening of French security.
The Paris prosecutor's office says it is opening a terrorism investigation into the incident on Thursday, which took place in the 18th district in northern Paris.
French officials say the suspect, who was wielding the butcher's knife, shouted "Allahu Akbar!" (God is Great) outside a police station in Goutte d'Or, near Montmartre, before police shot and killed him.
Bomb disposal experts were brought in after wires were seen extending from his body, but officials later said a belt he was wearing did not contain any explosives.
His fingerprints were found to match fingerprints on police files after an arrest for theft in the south of France in 2013.
Anti-terror police and French intelligence services are treating the incident as a case of attempted murder.
Following the attack, a cordon was been set up around the area, and security was boosted at schools and on public transport networks in the city.
Terror fears: By Hugh Schofield, BBC News, Paris
According to the prosecutor, it was at 11:30 that the man approached the police station in the Goutte d'Or before being shot.
According to police accounts, it was also at 11:30 - exactly a year ago - that the Kouachi brothers began their attack on Charlie Hebdo.
The presumption of a link must be very strong, especially after the authorities confirmed that this was for them a terrorist incident.
Was the man intent on striking a deadly counterblow to the commemorations that are going ahead this week?
If so, it was a feeble gesture compared with what happened a year ago - and of course with the 13 November attacks. But that in itself is significant. For a jittery French public, it shows that jihadism comes in all shapes: grand organised conspiracies at one end, small individual acts at the other.
But they too can kill.
Three days of attacks brought bloodshed to Paris and its surrounding areas last January.
The three attackers were shot dead by police, but questions remain about their jihadist contacts and possible accomplices in the Middle East.
A Paris court sentenced an alleged French IS recruiter in absentia on Thursday to 15 years in prison.
Salim Benghalem, 35, was freed from a French jail in 2010 and is believed to be in Syria. He was said to have been part of a jihadist network in Paris that includedCherif and Said Kouachi, the two Charlie Hebdo gunmen.
Three police officers were among the 17 victims of the gunmen on 7-9 January, 2015.
On Thursday, the French president said the officers had "died so that we could live in freedom".
But with France also still mourning the deaths of 130 people in jihadist attacks in Paris in November, he also used his speech to call for greater co-operation between the security services.
Since a state of emergency was imposed on the night of 13 November, police have brought to light 25 offences related to terrorism, he added.
Image copyrightReutersImage captionFrench police check a pedestrian as they secure the area after a man was shot dead at a police station in the 18th district in Paris
President Hollande said the rules for police use of firearms were also being revised, so that gunmen could be tackled more effectively.
Earlier, Parisians laid flowers and lit candles at the former office of Charlie Hebdo magazine, where a plaque was unveiled on Tuesday.
A second plaque was installed where a police officer was shot, and a third at the Jewish supermarket.
On Saturday, a fourth plaque will be unveiled in the southern suburb of Montrouge, where one of the gunmen shot dead a policewoman.
The commemorations will culminate in a public event on Sunday in the Place de la Republique, where Parisians gathered in the wake of the attacks.
A 35ft (10m) oak "remembrance tree" will be planted in the square and veteran French musician Johnny Hallyday will perform Un Dimanche de Janvier (One January Sunday), a song recalling the vast march in Paris that followed the attacks.
Sales of Volkswagen-branded vehicles fell 2.4% globally in November the wake of the emissions scandal, the German carmaker said on Friday.
The total for the 11 months of 2015 was down 4.5% compared with last year.
The annual tally was likely to fall short of last year's total as a result.
VW-brand board member Juergen Stackmann said: "In view of the current challenging situation, I don't believe VW will be able to make up the gap in the remaining days of the year."
Volkswagen said it sold 496,100 VW-brand cars worldwide in November.
Sales plunged in Brazil, with a 51.4% fall, and slid by 31.8% in Russia, although economic problems in both countries were largely to blame for those declines rather than the emissions scandal.
The VW brand delivered 6.12 million cars in total last year.
The company said last week that US sales fell 24.7% in November compared with the same month last year.
Volkswagen group chairman Hans Dieter Poetsch said on Thursday that a "chain of errors" led to the emissions scandal and that the entire company was now focused on regaining the trust of customers.
In September, US regulators found that some VW diesel cars had a "defeat device" - or software - to cheat emissions tests.
Image copyrightGetty Images
The company said the situation arose when it decided to launch a large-scale promotion of diesel vehicles in the US in 2005, but found it impossible to meet strict emissions limits in force in that country in time.
Mr Poetsch said: "No business justifies crossing legal and ethical boundaries."
Chief executive Matthias Mueller said he was confident that customers would overcome their reluctance to buy the group's vehicles in the coming weeks.
Dramatic footage has been released of a raid on the Spanish home of a British man, accused of running Europe's largest drug-trafficking network.
Robert Dawes is being held by French authorities on suspicion of trafficking over a tonne of cocaine worth €200m (£145m).
The 44-year-old, from Nottinghamshire, is also being investigated over a series of murders in the Netherlands.
The international operation has seen a further 50 arrests.
Image copyrightGuardia CivilImage captionSpanish police raided Robert Dawes' home on the Costa del Sol last month
Mr Dawes is accused of running Europe's "largest criminal organisation dedicated to drug trafficking, money laundering and murder", Spanish police said.
Image copyrightGuardia CivilImage captionRobert Dawes, originally from Sutton-in-Ashfield, Nottinghamshire, was picked up by Spain's Guardia Civil on a European arrest warrant
Police believe he was working with well-known South American drug cartels and the Italian Mafia, and was exporting large quantities of heroin to the UK from Afghanistan and Turkey.
He is also being investigated over a "wave" of drug-related murders in the Netherlands.
Mr Dawes was arrested last month and extradited to France after police raided his home in Benalmadena on the Costa del Sol.
The international police operation has also seized boats and planes.
Image copyrightGuardia CivilImage captionThe cocaine seized in France was worth an estimated 200m euros
Mr Dawes, who is originally from Sutton-in-Ashfield, was wanted for international drug trafficking.
He and his brother John were linked to Nottinghamshire kingpin, Gary Hardy, who was jailed for 20 years for drugs offences in 2008.
Image copyrightGuardia CivilImage captionRobert Dawes lived "in luxury", according to Spanish authorities
Reuters
