British attitudes towards immigration are “b******t” and the Government’s policies have put migrants’ lives at risk, a United Nations investigator has said.

François Crépeau, a Canadian who is the UN’s special rapporteur for migrants’ rights, also said it would be “not cool” if the UK Independence Party was able to influence policy, or formed part of a future government.

Speaking ahead of a fact-finding trip to Italy, where migrants have been arriving in increasing numbers from nations including Syria, Iraq and Eritrea after risking their lives on sea crossings, he criticised the Home Office for sending only one official to take part in a European search and rescue mission to prevent deaths in the Mediterranean Sea.

In the latest attack on the UK by a UN official, Mr Crépeau said politicians here ought to stand up to the public and dispel what he described as myths about migration.

In an interview with The Independent, he said: “The fantasy is that there is a core British culture that was created probably 2,000 years ago and carried on, and now it’s being threatened by all those barbarians that are coming to our gate.

 “This is utter b******t, but who is going to say this? That is why I think we have a problem with political conversations that we can’t have.”

In apparent praise for the governments of Tony Blair, Mr Crépeau said it was a “multicultural, diverse, open society” which created “Cool Britannia” in the 1990s.

“If Britannia is ruled by the Ukip, or with Ukip-type policies, it is not going to be cool,” he added.

Mr Crépeau’s outspoken remarks follow those of his colleague, Rashida Manjoo, a South African who is the special rapporteur on violence against women, who earlier this year said the UK had an “in-your-face, boys' club sexist culture" which led to a "marketisation of women's and girls' bodies."

And last year, the Brazilian Raquel Rolnik, special rapporteur on adequate housing, attacked the Coalition’s flagship housing benefit reforms, describing the so-called “bedroom tax” as a “shocking” breach of human rights.

Mr Crépeau’s comments came in an interview about the scaling down of a search and rescue operation launched by Italy following the deaths last year of 366 migrants off the coast of the island of Lampedusa.

The mission has been replaced by a patrol with a third of the budget of its predecessor, in a move which Amnesty International has claimed could put thousands of lives at risk.

One Home Office official was sent to join the new task force, after the Government said stopping search and rescue missions would deter migrants from attempting risky journeys to reach Europe.

Mr Crépeau, a professor of law, rejected that analysis, and accused European governments of establishing economies which benefited from a type of migrant slave labour.

He said: “Not supporting search and rescue operations means letting them die. This is what happens, if you don’t search and rescue them; they die.

“If we accept that, I think we go well beyond the moral boundaries of our political system.

“We have found a system to subsidise a series of sectors of our economies by people who have no power and can be exploited at will. This was the slavery system in the old days.”

Ukip immediately rejected his claims. Nigel Farage, the party’s leader, said: "More people came to Britain in 2013 than came between 1066 and 1950. That gives you a sense of perspective of where we are with this, so he is talking utter baloney.

"He is just not living in the real world. Britain is one of the most relaxed countries in the whole of Europe on immigration, but not with numbers like this."

David Coburn, a Ukip MEP, added: "The man is talking nonsense. The cultural aspect to immigration is very important but our major concern is economic.

"It is the usual tosh. He has no understanding of the economic problems that this is causing the United Kingdom. And as for the cultural aspect, quite frankly he knows nothing of our country and it's not for him to decided what we feel."

Conservative MP Dominic Raab added: "To claim the British public sees immigrants as ‘barbarians’ because it is ‘gripped’ by a 2,000 year old cultural ‘fantasy’ is offensive bigotry. Monsieur Crepeau is aping the very prejudice he is supposed to be fighting."

The Telegraph