Twilight star Robert Pattinson reportedly heckled a US comedian who mocked Heath Ledger's death in his act.

According to Us Weekly, the British actor became incensed when an unnamed comic at a Los Angeles comedy club collapsed on stage and faked convulsions while impersonating Ledger.

Pattinson, who was at the club with friends, reportedly yelled at the comedian: "F**k you! You suck! Leave Heath Ledger alone!"

A source added: "Robert and his friend went nuts yelling at him... The comic didn't know who it was, but I'm sure he found out later!"