Comedian Ricky Gervais has issued a stark warning on the perils of being a celebrity in the age of Instagram.

The Office star told the Sunday Mirror how an over-eager fan ambushed him in a public toilet while at a boxing match in the USA.

He said: "I went to see a title fight with Joe Calzaghe in New York, I went to the loo and this guy is like, 'Hey man, can I have a picture?' Arm straight round me, doing a selfie while I'm in the middle of doing a wee.

"I didn't even have a chance to say 'Can we leave it a minute, mate?' There's lots of testosterone at those things, you don't want to say no.

"All I could think was, 'How wide-angled was that lens? What did he get in?'."

More recently, Ricky has joined forces with US comedy stalwart Tina Fey in the newly released film, Muppets Most Wanted, in which he plays Dominic Badguy, a henchman for an evil Russian frog.

He said of his experience making the film: "I wanted to keep hugging them all and rub their pot bellies, and I kept scratching their heads thinking they'd like it. It's a man's hand!"