But he stopped short of saying sorry to the city's Islamic population

David Cameron today hit out at the 'complete idiot' TV pundit who claimed Birmingham was 'totally Muslim' and 'non-Muslims just simply don't go in',

Steve Emerson made the bizarre comments on Fox News in the US - also claiming there were religious police squads roaming the streets of London who 'seriously wound' people in non-Muslim dress.

It sparked bafflement on Twitter under the hashtag #FoxNewsFacts, with users suggesting his theory was about as likely as Brummie TV presenter Adrian Chiles being a radical cleric.

Mr Cameron said he thought it must be April Fools' Day, adding: ‘When I heard this, frankly I choked on my porridge. This guy is clearly a complete idiot.'

He added: ‘Now, he started with an apology – that’s not a bad place to start. But what he should do is actually look at Birmingham and see what a fantastic example it is of bringing people together of different faiths and different backgrounds and actually building a world class brilliant city.’

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Grovelling: Terrorism pundit Steve Emerson (left) apologised after claiming Birmingham (right) was 'totally Muslim' and 'non-Muslims don't go in'. He has now pledged a donation to the city's children's hospital

David Cameron said when he heard the comments he 'thought it must be April Fools’ Day', adding: 'I choked on my porridge'

In reality, 22 per cent of people from Birmingham are Muslim, according to the 2011 census, fewer than half of the 46 per cent who regard themselves as Christian.

Birmingham is the area with the ninth-highest Muslim population in Britain, beaten by four London boroughs alongside Slough, Luton, Bradford and Blackburn.

Mr Emerson has now apologised to Birmingham's 1.1million people, insisting the city is 'beautiful' and pledging a donation to the Birmingham Children's Hospital.

But he stopped short of offering any sort of apology directly to the city's 234,000 Muslims, who he appeared to lump into the same category as extremists in his rant.

The 'expert' has run a group called The Investigative Project on Terrorism for 20 years and written books with titles such as 'Jihad Incorporated' and 'The Terrorists Living Among Us'.

Critics have accused him of inaccuracies and encouraging Islamophobia, yet he is still called upon regularly by news networks and congressional committees in the U.S.

Pundit: Mr Emerson (right) made the claim in an interview with Fox News. He has run a 'project on terrorism' for 20 years and is regularly called on by news outlets, though his critics accuse him of inaccuracies

Slight: In fact, Birmingham has twice as many Christians (46 per cent) as Muslims (22 per cent). Mr Emerson stopped short of apologising to the city's Islamic population, who he appeared to lump in with extremists

His blunder came in a wide-ranging Fox News interview about how to react to the Charlie Hebdo attacks in Paris.

'In Britain, it's not just no-go zones,' he claimed. 'There are actual cities like Birmingham that are totally Muslim where non-Muslims just simply don't go in.'

As the interviewer's eyes widened in surprise, he added: 'And parts of London, there are actually Muslim religious police that actually beat and actually wound seriously anyone who doesn't dress according to Muslim, religious Muslim attire.'

Mr Emerson initially seemed happy with the factual accuracy of his performance, posting the entire interview on his website.

But once told of his fairly significant error, he apologised.

'I have clearly made a terrible error for which I am deeply sorry,' he told ITV News.

Bafflement: In time-honoured fashion, an ironic hashtag about the gaffe was soon circulating on Twitter

'My comments about Birmingham were totally in error, and I am issuing an apology and correction on my website immediately for having made this comment about the beautiful city of Birmingham.

'I do not intend to justify or mitigate my mistake by stating that I had relied on other sources because I should have been much more careful.

'I intend to make a donation to a Birmingham charity called the Birmingham Children’s Hospital.'

Thousands of Twitter users were suggesting alternative 'Fox News facts' - with a similar level of factual accuracy - within hours of the gaffe.

One suggested Cardiff had dispensed with cars and was now known as Diff, while another said all the walls in Cornwall were made from corn.

Jokes: Commenters on Twitter said the theory was about as likely as TV presenter Adrian Chiles being a radical cleric, or Mecca bingo halls being a substitute for the holy city of pilgrimage

Because Birmingham was 'totally Muslim' it would have to remove 'ham' from its name, suggested other users.

Factual accuracy aside, many defended the city against what they took to be a crude Islamophobic attack.

Birmingham City Council Labour member Waseem Zaffar ‏wrote: 'Birmingham is a diverse city with people from 187 countries making it home since 2007'.

And school deputy head teacher wrote: 'I live in a multicultural city. I work in a multicultural school. I feel at home. I love it. Birmingham is vibrant because it is diverse.'