Clooney told to "dump" Sarah Larson

An anonymous phone caller has told George Clooney to dump his girlfriend Sarah Larson, reports say.

The caller is alleged to have told Clooney: "Dude, your friends asked me to give you a message, 'Dump the b**** before you're sorry'."

However, Clooney insisted that his friends wouldn't play a prank on him.

"It's not a prank - none of my friends would do that," he said.

The 46-year-old has asked a police officer, who also acts as his chauffeur, to track down the man who made the call from a pre-paid mobile phone.

Pictures of Larson surfaced on the internet last week that showed her wearing a bondage outfit.

"They say that I'm a stripper," the 29-year-old said. "There's a ton of stuff about that. I've never been a stripper. You know, just because I'm from Las Vegas, I must be a stripper. Because I'm a cocktail server, that means I'm an escort."