Birmingham is a “totally Muslim” place where “non-Muslims just simply don’t go”, a self-proclaimed terrorism expert told the US Fox News channel, sparking a tidal wave of mockery.

Steve Emerson’s comments saw the Twitter hashtag foxnewsfacts trend worldwide on Twitter as people made things up about Birmingham, Fox News or pretty much anything.

Mr Emerson was taking part in a television discussion about supposed Muslim-controlled areas in Europe.

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

“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.”

He said there were sharia courts in Birmingham “where Muslim density is very intense, where the police don't go in, and where it's basically a separate country almost, a country within a country”, adding that the UK government did not “exercise any sovereignty” there.

Jeanine Pirro, the host of the Judge Pirro show, replied: “You know what it sounds like to me, Steve? It sounds like a caliphate within a particular country.”

Their laughable remarks saw British politicians, leading journalists, novelists and others take part in the general derision of the news channel on Twitter.

Labour MP Tom Watson retweeted a message which said: “Birmingham is home of Black Sabbath and other terrifying Muslim musicians. #FoxNewsFacts.”

Author Mirza Waheed tweeted: “Wali Sheikh Peer was a Muslim dramatist from Englistaan.”

Fellow writer Irvine Welsh said: “I warn you, @FoxNews, I have an Ocean Colour Scene download and I'm not afraid to use it! (Well, maybe a wee bit...).”

Broadcaster Robin Lustig came up with: “Jihadi extremists have forced the city of Oxford to rename the Thames the River Isis. #foxnewsfacts”

And even ITN newsreader Alastair Stewart, joined in “If you do not clean your finger-nails regularly, potatoes will grow in your stomach, crush your lungs & suffocate you. #FoxNewsFacts,” he wrote.

He added: “There will be senior managers in Fox News who don't get what all the fuss is about, nor understand the humour.”

Sean Kelly, who describes himself as a “regular bald guy”, tweeted: “Extremist rock group Showaddywaddy have reformed and changed their name to Jihaddywaddy #foxnewsfacts.”

Mr Emerson later apologised but did not provide a full explanation of how he came to make the remarks.

He told ITV News: “I have clearly made a terrible error for which I am deeply sorry. 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. There was no excuse for making this mistake and I owe an apology to every resident of Birmingham.

“I am not going to make any excuses. I made an inexcusable error. And I am obligated to openly acknowledge that mistake.”