LONDON (AFP) - The BBC apologised on Thursday for accidentally showing an image of Britain's Prince William with a penis drawn on his head.

The blunder happened when the broadcaster's breakfast TV show aired a clip of a promo video for a comedy group who were appearing later on the programme.

The image of the second-in-line to the British throne, with a beard and moustache scrawled in black pen onto a picture of the prince in a newspaper flashed up on the screen for a couple of seconds.

He had also acquired glasses, missing teeth and a penis on his head.

It had apparently been missed by BBC editors, but was spotted by several viewers.

"Yup, that's a penis on Prince William's head," one viewer tweeted. "Outrageous."

The BBC apologised for the gaffe, stressing that the "offending material" was not produced by the broadcaster.

"This image was shown fleetingly within a comedy promotional video for Barbershopera, a humorous barbershop group, who were appearing later on in the programme," a BBC spokeswoman said.

"The material was provided by Barbershopera but we failed to spot the offending material within it. We apologise for this."

Prince William, 31, is currently on paternity leave from his job as a search-and-rescue helicopter pilot with the Royal Air Force after his wife Kate gave birth to their son on July 22.

Prince George, the couple's first child, is third in line to the throne.