Sir Paul McCartney has recorded a rap song to encourage people to go vegetarian.

The Beatles frontman enlisted the help of his famous friends, Joanna Lumley, Twiggy, Sharleen Spiteri and Woody Harrelson to shoot a video of him rapping to promote a Meat-Free Mondays campaign in an attempt to get people all over the world to make their diet flesh-free once a week.

In the video, which was posted on YouTube, he says: ''I need your help, all I want you to do is just log in on pledge.meatfreemondays.com and pledge your support to the idea of meat-free Mondays.

''Please do it. We'll send all these pledges to the politicians, and then they'll do something about it.''

The 72-year-old star's musical appeal to ditch meaty treats sees him holding up signs emblazoned with the message ''Meat-Free Monday'' and he gets very animated by clicking his fingers as well as clapping his hands throughout.

TV and radio presenter Fearne Cotton and Paul's daughters, designer Stella McCartney and Mary also make an appearance in the music video.

More than 843,000 people - including famous faces such as Gwyneth Paltrow, Mark Ruffalo, Kevin Spacey and Ricky Gervais - have signed up to the pledge.

Paul's plea comes ahead of the United Nations climate summit tomorrow (23.09.14) in New York.

UN Secretary-General Ban Ki-moon is gathering together global leaders - the first time Heads of State will have come together to discuss climate change since Copenhagen in 2009.

The summit is being held to jump-start the climate negotiations that are due to conclude with an ambitious global treaty in December 2015.