The stars are signing off from all social media platforms, and will not return until an AIDS charity - Keep a Child Alive, which is spearheaded by Alicia ' has raised $1 million.

For the campaign, the stars have filmed 'last tweet and testament' videos and will appear in adverts showing them lying in coffins to represent their 'digital deaths'.

Alicia will also be joined by her husband Swizz Beatz, Kim and Khloe Kardashian, Usher, Jennifer Hudson, Ryan Seacrest, Elijah Wood, Serena Williams in the campaign, which will start on Wednesday (01.12.10), which is World AIDS Day.

Alicia said no one she has approached had turned her down, explaining: 'Once I got people on the phone and I was able to paint the concept for them, everybody was in.'

Leigh Blake, who is president and co-founder of the charity, added: 'We're trying to sort of make the remark: Why do we care so much about the death of one celebrity as opposed to millions and millions of people dying in the place that we're all from?'

Almost all the stars involved have over a million followers on micro-blogging site twitter, with Gaga alone having 7.2 million.

Leigh added: ' have a feeling that Gaga is going to raise it all by herself."