Madonna and Annie Lennox join forces

Madonna has signed up to appear on a new charity single written by Annie Lennox to raise the awareness of HIV in South Africa.

The Eurythmics singer penned 'Sing' to raise money for the Treatment Action Campaign, which was launched in 1998 to treat those suffering with the infection and reduce the numbers that do.

Twenty three female artists will appear on the record; KT Tunstell, Joss Stone and Celine Dion have already agreed to take part.

Lennox started campigning for the cause when she worked for Nelson Mandela's 4664 Aids charity two years ago.