The self-proclaimed Fox News “terror expert” who described Birmingham as a “no-go area for non-Muslims” has compared what he has gone through in the wake of the comments to waterboarding.

Appearing on Sky News to apologise for what he called his “sloppy research” and “inexcusable error”, Steve Emerson said he “deserved the pain and hurt” he has experienced since.

“Hearing it over when you played it was like waterboarding, I guess,” he said.

The pundit’s comments during a live TV broadcast on Sunday – that “there are actual cities like Birmingham that are totally Muslim, where non-Muslims just simply don't go in” – were widely derided and drew a response from David Cameron himself.

In the full interview, Emerson also turned his attention to the UK capital, saying: “(In) parts of London there are actually Muslim religious police who beat and actually wound seriously anyone who doesn't dress according to Muslim religious attire.”

Speaking to ITV News, the Prime Minister said Emerson was “clearly a complete idiot”.

“When I heard this, I choked on my porridge and I thought it must be April Fool's Day,” he said.

“Now he has started with an apology, that's not a bad start, but what he should do is look at Birmingham and see what a fantastic example it is of bringing people together of different faiths, different backgrounds and actually building a world-class, brilliant city with a great and strong economy.”

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Emerson’s new comments come in the wake of a CIA torture report that found US security services used waterboarding among other violent acts of interrogation on suspected terrorists.