Last updated at 19:36 10 February 2008

Inbreeding among immigrants is causing a dramatic rise in birth defects, a government minister has warned.

Referring to the culture of Muslim arranged marriages between cousins, environment minister Phil Woolas said: "If you have a child with your cousin the likelihood is there'll be a genetic problem."

Mr Woolas, whose views were supported today by medical experts, said the practice did not extend to all Muslim communities and that most cases occur in families from rural Pakistan, where up to half of all marriages are thought to involve first cousins.

According to today's Sunday Times, the minister, who represents Oldham East and Saddleworth said: "If you talk to any primary care worker they will tell you that levels of disability among the . . . Pakistani population are higher than the general population. And everybody knows it's caused by first cousin marriage.

"That's a cultural thing rather than a religious thing. It is not illegal in this country.

"The problem is that many of the parents themselves and many of the public spokespeople are themselves products of first cousin marriages.

"It's very difficult for people to say 'you can't do that' because it's a very sensitive, human thing."

Today he was backed by chief whip Geoff Hoon, who said: “He was commenting on a particular problem about cousins marrying first cousins.

"It is important that we look at that in terms of scientific expertise and the extent to which it is actually causing problems.

"But it obviously is a very sensitive matter and no one, no one, would suggest this is a problem for the wider Muslim community.

"I am confident that what he has said will have been said with sensitivity and with proper regard to his Muslim constituents and Muslims right across the United Kingdom."

"If you are supportive of the Asian community then you have a duty to raise this issue.

"Awareness does need to be raised but we are very aware of the sensitivities," he added,

Mr Woolas said the issue is "very sensitive" and rarely debated and was supported by Labour MP for Keighley, Ann Cryer, who called for the NHS to do more to warn parents of the dangers of inbreeding.

She said: “This is to do with a medieval culture where you keep wealth within the family.”

“If you go into a paediatric ward in Bradford or Keighley you will find more than half of the kids there are from the Asian community. Since Asians only represent 20 per cent-30 per cent of the population, you can see that they are over represented.

“I have encountered cases of blindness and deafness. There was one poor girl who had to have an oxygen tank on her back and breathe from a hole in the front of her neck.

“The parents were warned they should not have any more children. But when the husband returned again from Pakistan, within months they had another child with exactly the same condition.”

Research for BBC2's Newsnight in November 2005 showed British Pakistanis accounted for 3.4 per cent of all births but have 30 per cent of all British children with recessive disorders.

The comments are likely to intensify the debate about multi-culturalism in Britain, sparked last week by claims by the Archbishop of Canterbury that the introduction of sharia law in Britain is 'inevitable'.

Pressure mounted on Dr Rowan Williams today as Cardinal Cormac Murphy-O'Connor, the leader of the Roman Catholic Church in England and Wales, insisted that migrants must obey the British legal system.