LONDON (Reuters) - Queen, Annie Lennox, Simple Minds, Amy Winehouse and some of Africa's top singers are among the stars expected to perform before Nelson Mandela and nearly 50,000 fans at a London concert on Friday.
The tribute to the elder statesman as he approaches his 90th birthday coincides with a disputed election in Zimbabwe, and the crisis in the southern African nation has overshadowed Mandela's visit to Britain.
The former South African president has been urged to speak out against Zimbabwe's leader Robert Mugabe, and four words of criticism in a speech at a dinner late on Wednesday -- "tragic failure of leadership" -- made headline news.
Mandela officially retired from politics nine years ago, but he is still a moral authority admired the world over.
Emmanuel Jal, a Sudanese hip-hop artist based in London who is also singing on Friday, said Mandela was "unique" among African leaders.
"He did not love power so much, and left it and gave it to someone else," he told Reuters.
Mugabe has pushed ahead with the vote despite international condemnation and a boycott by the opposition leader prompted by a wave of deadly attacks on his supporters.
Mandela will hope to be able to concentrate on the celebrations on Friday evening, when 46,664 people will join him for a charity concert to raise funds for his HIV/AIDS organization 46664 named after his prison number.
The event, in London's Hyde Park, comes 20 years after a tribute gig at Wembley Stadium to honor Mandela when he was still behind bars for his stand against apartheid.
Jerry Dammers, who helped organise the 1988 concert and whose song "Free Nelson Mandela" became a banner for the anti-apartheid movement in Britain in the 1980s, will also take the stage.
He will be joined by California tenor Josh Groban, who had 2007's biggest-selling album in the United States with "Noel."
All eyes will be on Winehouse, who is due to appear despite being diagnosed with a "touch of" lung condition emphysema earlier this month.
The 24-year-old has fought drug addiction and her husband Blake Fielder-Civil is in prison awaiting sentence for attacking a pub landlord and conspiring to pervert the course of justice.
(Reporting by Mike Collett-White)
For a timeline on Nelson Mandela, visit: here x=20080616094404.xml&tn=Mandela%20at%2090