An emotional Nelson Mandela said he was "honoured" yesterday as his statue was unveiled opposite the Houses of Parliament.

The former South African president was visibly moved when Gordon Brown described the artwork as a "beacon of hope" for the oppressed around the world.

The Prime Minister said: "Nelson Mandela is one of the most courageous and best-loved men of all time. You will be here with us always."

A crowd of thousands gathered in central London to pay tribute to the veteran campaigner.

They included Tory leader David Cameron, Foreign Secretary David Miliband and former Deputy Prime Minister John Prescott.

Mr Mandela was accompanied by his wife, Graca Machel, who has been made a dame for her humanitarian work.

The 89-year-old walked unsteadily on to the stage, beaming at the rapturous reception he received from the crowd in Parliament Square.

After the unveiling, he was escorted to the podium by Mr Brown, to whom he wished "wisdom and strength" as leader of the UK.

Mr Mandela told the crowd: "It's an honour for us to be with you on the occasion of the unveiling of this statue today. We never dreamed we would all be here today.

"Though this statue is of one man, it should in actual fact symbolise all those who have resisted oppression, especially in my country."

Mr Mandela added that he and a fellow anti-apartheid leader had wished for this day after a visit to Britain in the Sixties.

"When Oliver Tambo visited Westminster Abbey and Parliament Square, we half joked that one day a statue of a black person would be erected here," he said.

Mr Brown said: "This statue is a beacon of hope. It sends around the world the most powerful of messages: that no injustice can last for ever, that suffering in the cause of freedom will never be in vain."

The statue, by the late Ian Walters, was originally to have stood in Trafalgar Square, but planning permission was refused by Westminster City Council and the Parliament Square site was chosen instead.

The appeal of Mr Mandela across the political spectrum was reinforced by the sight of Mr Cameron laughing and joking before the ceremony with left-wing former Labour MP Tony Benn.