More than 360,000 people have backed a call for Donald Trump to be banned from the UK after he suggested Muslims should be barred from America.
Thousands rushed to sign a petition on the Parliament website as British politicians lined up to condemn the remarks.
The property tycoon and reality TV star, who is seeking the Republican nomination for next year's presidential election, provoked widespread anger and ridicule after demanding a block on Muslims entering the US and claiming parts of London were "so radicalised" that police were "afraid for their own lives".
Downing Street has made clear that David Cameron regards the presidential hopeful's comments as "divisive, unhelpful and quite simply wrong".
Chancellor George Osborne branded them "nonsense", but dismissed calls for Mr Trump to be excluded from the UK, saying it was better for his views to be challenged in debate.
Asked about the issue as he stood in for Mr Cameron at PMQs, Mr Osborne said: "I think the best way to defeat nonsense like this is to engage in robust, democratic debate and make it very clear his views are not welcome."
London mayor Boris Johnson delivered the strongest riposte, saying the remarks rendered Mr Trump unfit for office.
"I think Donald Trump is clearly out of his mind if he thinks that's a sensible way to proceed," he said. "You can't ban people going to the US in that way, or indeed to any country.
"What he's doing is playing the game of the terrorists and those who seek to divide us. That is exactly the kind of reaction they hope to produce.
"When Donald Trump says there are parts of London that are no-go areas, I think he is betraying a quite stupefying ignorance that makes him frankly unfit to hold the office of the president of the United States."
Mr Johnson joked: "I would invite him to come and see the whole of London and take him round the city, except that I wouldn't want to expose Londoners to any unnecessary risk of meeting Donald Trump."
Scottish First Minister Nicola Sturgeon stripped Trump of his membership of the GlobalScot business network, saying that he was no longer fit to act as a business ambassador for Scotland.
He has also been relieved of his honorary degree from Robert Gordon University (RGU) in Aberdeen, where he was awarded a doctorate of business administration in October 2010.
Any issue on which a petition exceeds six-figure support is considered for debate by MPs.
The petitions committee is not due to meet again until January 5.
Suzanne Kelly, who originally lodged the document, said it was "one of many little acts of defiance" against Mr Trump that had since ballooned.