Sir Paul co-wrote the song with musician Dave Stewart

They are backing Nelson Mandela's campaign - named 46664 after his former prison number - which culminates in a concert in Cape Town on 29 November.

Sir Paul has written a song with fellow musician Dave Stewart, while Gabriel and Stevens will perform together.

Beyonce and U2's Bono are also backing the event, being televised by MTV.

Beyonce will play at the concert on 29 November

The show at Cape Town's Greenpoint Stadium also features artists such as Ms Dynamite, Queen, Anastacia, The Corrs and Youssou N'dour.

South African artists appearing include Ladysmith Black Mambazo, Johnny Clegg and Angelique Kidjo.

Gabriel will perform his song Biko, written as a tribute to anti-apartheid activist Steve Biko, who was killed in 1977, in front of a South African audience, for the first time.

The show will air on MTV on World Aids Day, 1 December, to a potential global TV audience of more than three billion in more than 90 countries.

Sir Paul has co-written a track called Whole Life with former Eurythmics member Stewart. The song, recorded at London's Abbey Road studios, can only be heard on the campaign website at www.46664.com.

The event, also backed by former US president Bill Clinton, actor Robert De Niro and chat show host Oprah Winfrey, is asking citizens around the world to pressure their governments to respond to Aids as an international emergency.

It is using internet and mobile phone technology to reach millions of potential supporters, who will be asked to give "one minute of your life" to Aids.