McCartney, 65, posed for a photograph for the People for the Ethical Treatment of Animals (PETA) organisation accompanied by the words: "I am Paul McCartney and I am a vegetarian".

It also features the quote: "Many years ago, I was fishing, and as I was reeling in the poor fish, I realized, 'I am killing him - all for the passing pleasure it brings me.'

"And something inside me clicked. I realized as I watched him fight for breath, that his life was as important to him as mine is to me."

PETA's Web site also features pictures of other celebrities, including Alicia Silverstone, Forest Whitaker and Joss Stone as part of its vegetarianism campaign.