Air turns blue as tweeters force an apology from BBC over swearing on Breakfast show

Viewers heard a disembodied voice exclaim “What the f*** is that?” at the start of an item during the programme yesterday morning.

Presenter Susanna Reid was introducing musical conductor John Wilson as a guest on the show when the gaffe occurred.

Neither the presenters nor Mr Wilson seemed to have heard the f-bomb as Ms Reid continued the interview without any interruption or pause.

The foul-mouthed outburst became a popular talking point online as users sent messages about the slip on Twitter.

Both Ms Reid and her co-host Charlie Staydt apologised for the gaffe at the close of the show.

The BBC said a microphone had been left on outside the studio which picked up the four-letter word.

A spokeswoman said: “We accidentally played out not-for-broadcast audio containing an audible swear word. The error was caused by a radio microphone inadvertently being left on outside our studio.

“Our presenters apologised on air as soon as the mistake was identified and we are reviewing our procedures accordingly.”

It is not the first time the BBC has been forced into an ignominious apology after expletives on air.

The show has previously had to apologise for broadcasting swear words when an uncensored tape of actor Christian Bale was mistakenly aired. Dame Helen Mirren and film director Nicolas Winding Refn also found themselves in hot water after using bad language on the programme.