Donald Trump faced universal anger and ridicule after he called for Muslims to be banned from the United States – and claimed that parts of London were “so radicalised” that police were “afraid for their own lives”.

Furious MPs and Muslim groups argued in response that anti-extremist legislation should be used to ban the billionaire Republican presidential hopeful from the UK if he attempts to visit Britain.

An online petition on Parliament's website demanding that Mr Trump is banned from the UK had more than 30,000 signatures first thing on Wednesday morning. The Government is obliged to respond to any petition with more than 10,000 signatories.

David Cameron took the unprecedented step of intervening in an American election by issuing a scathing rebuke to the front-runner to gain the Republican nomination for the presidency. The Prime Minister was backed by leaders of all political parties, the candidates to become London mayor, the Metropolitan Police, think-tanks and influential Muslims.

Mr Trump provoked international outrage after saying that there should be “a total and complete shutdown” of Muslims entering the US following last week’s terrorist attack on a Californian social service centre in which 14 people died. He sought to justify his comments by claiming that police were frightened to venture into parts of the British and French capitals because of Islamic extremism.

“They have sections in Paris which are radicalised where they police refuse to go there because they’re petrified. We have places in London and other places that are so radicalised the police are afraid for their own lives,” he said.

Trump on Muslims

Mr Cameron’s official spokeswoman declined to say whether his comments might lead to him being barred from the UK. But she said: “The Prime Minister completely disagrees with the comments made by Donald Trump, which are divisive, unhelpful and quite simply wrong.”

Jeremy Corbyn, the Labour leader, denounced the remarks as “an attack on democratic values” and an “affront to common humanity”.

The Scottish First Minister, Nicola Sturgeon, said: “Donald Trump’s comments are obnoxious and offensive, and have rightly been condemned by people across the political spectrum.”

Tim Farron, the Liberal Democrat leader, said: “For someone trying to be president of America it frankly shows why he is utterly unsuited for the role.”

Donald Trump's most controversial quotes Show all 14 1 /14 Donald Trump's most controversial quotes Donald Trump's most controversial quotes On Isis: "Some of the candidates, they went in and didn’t know the air conditioner didn’t work and sweated like dogs, and they didn’t know the room was too big because they didn’t have anybody there. How are they going to beat ISIS?" Getty Donald Trump's most controversial quotes On immigration: "I will build a great wall — and nobody builds walls better than me, believe me —and I’ll build them very inexpensively. I will build a great, great wall on our southern border, and I will make Mexico pay for that wall. Mark my words." Reuters Donald Trump's most controversial quotes On Free Trade: "Free trade is terrible. Free trade can be wonderful if you have smart people. But we have stupid people." PAUL J. RICHARDS | AFP | Getty Images Donald Trump's most controversial quotes On Mexicans: "When Mexico sends its people, they’re not sending their best. They’re sending people that have lots of problems. They’re bringing drugs. They’re bringing crime. They’re rapists." Getty Donald Trump's most controversial quotes On China: "I just sold an apartment for $15 million to somebody from China. Am I supposed to dislike them?... I love China. The biggest bank in the world is from China. You know where their United States headquarters is located? In this building, in Trump Tower." Getty Images Donald Trump's most controversial quotes On work: "If you're interested in 'balancing' work and pleasure, stop trying to balance them. Instead make your work more pleasurable." AP Donald Trump's most controversial quotes On success: "What separates the winners from the losers is how a person reacts to each new twist of fate." Donald Trump's most controversial quotes On life: "Everything in life is luck." AFP Donald Trump's most controversial quotes On ambition: "You have to think anyway, so why not think big?" Getty Images Donald Trump's most controversial quotes On his opponents: "Bush is totally in favour of Common Core. I don't see how he can possibly get the nomination. He's weak on immigration. He's in favour of Common Core. How the hell can you vote for this guy? You just can't do it." Reuters Donald Trump's most controversial quotes On Obamacare: "You have to be hit by a tractor, literally, a tractor, to use it, because the deductibles are so high. It's virtually useless. And remember the $5 billion web site?... I have so many web sites, I have them all over the place. I hire people, they do a web site. It costs me $3." Getty Images Donald Trump's most controversial quotes On Barack Obama: "Obama is going to be out playing golf. He might be on one of my courses. I would invite him. I have the best courses in the world. I have one right next to the White House." PA Donald Trump's most controversial quotes On himself: "Love him or hate him, Trump is a man who is certain about what he wants and sets out to get it, no holds barred. Women find his power almost as much of a turn-on as his money." Getty Images Donald Trump's most controversial quotes On America: "The American Dream is dead. But if I get elected president I will bring it back bigger and better and stronger than ever before and we will make America great again." GETTY

Calls were growing for legislation designed to ban radical preachers from the UK to be applied to Mr Trump if he attempted to fly to Britain.

The Muslim Council of Britain said: “We have been told that those who espouse hatred have no place in the UK. We expect the same rules to apply to [Mr Trump] if he tries to enter the UK.”

Sunder Katwala, the director of the British Future think-tank, said: “Until Trump retracts these highly prejudiced comments, there is a good case for making clear he would be refused entry to the UK by the Home Secretary.”

Piers Morgan on Donald Trump

And the Tory MP Sarah Wollaston said: “If he doesn’t retract the comments, then it is reasonable to question whether there are grounds to ban him from the UK.”

In a rare intervention into politics, the Metropolitan Police rejected his comments about London’s security. A spokeswoman said: “Mr Trump could not be more wrong. Any candidate for the presidential election in the United States of America is welcome to receive a briefing from the Met Police on the reality of policing London.”

Boris Johnson, the London Mayor, mocked the tycoon, remarking: “The only reason I wouldn’t go to some parts of New York is the real risk of meeting Donald Trump.” He said: “Donald Trump’s ill-informed comments are complete and utter nonsense.”

Donald Trump, pictured at the 2015 Women’s British Open at Turnberry, says London police fear for their lives (AP)

The Conservative MEP for London, Syed Kamall, invited Mr Trump to stay as a “house guest” with him to get to know London, but said he did not expect a return invitation as he would be barred from the US if Mr Trump became president.

As public disgust at the US presidential hopeful’s comments grew in Scotland, an Aberdeen university that once awarded him an honorary degree said it was “considering” whether to revoke it. By 5pm more than 7,500 people had signed a petition calling on Robert Gordon University to strip Mr Trump of the award.

Mr Trump defended his call for a ban on Muslim visitors to the US, but clarified he would keep the border open to American Muslims returning from trips.

He insisted in television interviews that the US was “at war” and likened his plan to steps taken by President Franklin D Roosevelt in the Second World War. “We have no choice but to do this. We have people that want to blow up our buildings, our cities,” he told ABC News.

Most legal experts said his plan would violate the constitution and international law.

Nihad Awad, executive director of the Council of American-Islamic Relations, said: “Donald Trump sounds more like the leader of a lynch mob than of a great nation like ours.”

Banned: Roll call of extremists

Dieudonné M’bala M’bala

The French comedian was banned from entering the United Kingdom for inciting racial hatred and making anti-Semitic comments. He came to prominence in the UK after a footballer celebrated a goal with the comedian’s trademark “quenelle” gesture, which has been likened to a Nazi salute. “I have been treated as public enemy No 1, when all I try to do is make people laugh.”

The French interior minister wants Dieudonne banned M'bala M'bala from the stage for what he says are racist and anti-Semitic performances. (AP)

Michael Savage

A right-wing US shock jock, he was on a list of 16 people banned from entering the UK revealed by then Home Secretary Jacqui Smith in 2009. He called the Koran a book of hate, and has suggested that some Muslims were in need of deportation. “You know, when I see a woman walking around with a burka, I see a Nazi.”

Geert Wilders

The Dutch far-right leader was banned from travelling to Britain in 2009 because his views “threatened community harmony” after he criticised the Koran as a fascist book. He returned to the country later in the year when he declared: “Islam is not a religion, it’s the ideology of a retarded culture”

Terry Jones