Banning Donald Trump from coming to the UK would risk turning him into a martyr, a Labour MP has claimed as the House of Commons debates the issue.
Paul Flynn said Mr Trump's call to ban Muslims from the US was "extremely dangerous" but barring him from the UK risked being seen as anti-American.
However, SNP MP Tasmina Ahmed-Sheikh said a ban would be justified on the grounds of "religious harmony".
UK MPs are debating a pro-ban petition, which has attracted 574,000 signatures
The tycoon, who is leading several opinion polls in the race to be the Republican candidate for President, called for a temporary ban on all Muslims entering the US in response to the shooting of 14 people in San Bernardino, California in December.
Mr Trump's comments were criticised across the political spectrum in the US and Europe. He caused further anger by claiming that areas of London and other parts of the UK have become so radicalised that they have become no-go areas for the police.
The "Ban Trump" petition states that the UK "has banned entry to many individuals for hate speech" and argues that the rules must be "fairly applied to the rich as well as poor".
A counter-petition, also being debated although it has not reached the 100,000 signature mark, argues that foreign nationals should not be banned "for their opinions on domestic actions" and that a ban would risk damaging US-UK relations given the possibility of a Trump victory in November's election.
Opening the debate in a crowded chamber, Mr Flynn said it would be wrong to ignore the ban petition, given that the "public was speaking with such a loud voice" and insisted the debate was not an attempt to "disrespect Americans or the American state".
He said some of those who signed the petition believed that Mr Trump's comments had incited acts of violence in the US.
Listing the names of some of those who had been banned by the UK authorities in recent years he said the risk of a ban would be that it would increase the publicity surrounding Mr Trump "100-fold".
Mr Trump's "prejudice" should be countered by "reasonableness, hospitality and courtesy", Mr Flynn told MPs. "We should not build him up by our attacks," he said.
"The great danger by attacking this one man is that we can fix on him a halo of victimhood," he said. "We give him the role of martyrdom which can seem to be an advantage among those who support him.
"The line will go out 'here are these foreigners interfering, telling us what to do'. I think that would be a grave error and allow our deliberations to be seen to be anti-American".
Tory MP Andrew Murrison said Mr Trump was a "ridiculous" figure but that to ban someone who had a chance of becoming US President could be construed as an "almighty snub" to the US.
And fellow Conservative Sir Edward Leigh said the UK had invited despots to the UK in the past who had done "far, far worse than anything Donald Trump can dream of" warning against "shutting down an honest debate about immigration".
But, backing a ban, Labour MP Tulip Siddiq said that Mr Trump's words "risks inflaming tensions between vulnerable communities" and those calling for this "poisonous and corrosive" man to be barred were speaking in "good conscience".
"I draw the line with freedom of speech when it actually imports violent ideology which is what I feel is happening," she said.
"The legislation exists to protect the public and the people of Britain from individuals such as this. If other people have been stopped from coming into the country the same rules need to apply to Donald Trump."
Key quotes from the debate
Labour MP Jack Dromey: "I don't think Donald Trump should be allowed within 1000 miles of our shores....Donald Trump is free to be a fool but he is not free to be a dangerous fool in Britain."
Labour MP Naz Shah: "I would give Donald Trump an open invitation to visit my constituency... I would invite him for a curry. I would welcome him, have a conversation with him and challenge him on his views."
Conservative MP Sir Edward Leigh: "Like it or not, he is quite a contender to be the head of state of the most powerful country on the planet, a country which is a vital ally of ours. We have welcomed to the country Saudi and Chinese leaders, not to mention Mr Ceausescu, whose crimes are far worse than anything Mr Trump can dream up."
And Ms Ahmed-Sheikh said Mr Trump's comments made the UK an "uncomfortable place" for her and other Muslims to live in.
"The home secretary has explicitly excluded 84 people for hate speech. My view is that Donald Trump should be number 85...We have a responsibility for peace and security to ensure that whoever comes in and out of our country is treated in the same way."
All public petitions which attract more than 100,000 signatures are considered for debate. Monday's debate is taking place in Westminster Hall, the Commons' secondary debating chamber, rather than the main Commons chamber itself. There will be no vote at the end of it.
The UK home secretary has the power to ban people from entering the country on grounds of national security, if they are thought likely to incite racial hatred or if they are deemed not to be "conducive to the public good".
Ahead of the debate, Trump International Links Scotland issued a statement saying MPs should be spending their time debating the problems facing the Scottish and UK economies.
"For the UK to consider banning someone who made a statement in America, about American borders during a US election campaign is ridiculous," said Sarah Malone, the company's executive vice president.
"Westminster is creating a dangerous precedent on this issue and is sending a terrible message to the world."