Overcoming poverty is not a gesture of charity but an act of justice, former president and freedom icon Nelson Mandela said at the Africa Standing Tall Against Poverty concert in conjunction with Live8 in Newtown on Saturday.

"While poverty persists, there is no true freedom."

Mandela addressed about 20 000 screaming fans at Mary FitzGerald Square in Johannesburg, saying the world was one of great promise and hope, but also of despair, disease and hunger.

He spoke directly to the leaders of the G8 nations who meet in Scotland next week, and urged them "not to look the other way."

"Recognise that the world is hungry for action, not words. Act with courage and vision."

Mandela said history and generations to come will judge the leaders by the decisions they make in the coming weeks.

He said they faced the most critical question that our world has had to face: "How do we remove the face of poverty from our world?

"Not to do this would be a crime against humanity against which I ask all humanity now to rise up."

The former president said as long as poverty, injustice and inequality persisted, no one could truly rest.

"We live in a world where knowledge and information have made enormous strides, yet millions of children are not in school.

"The Aids pandemic threatens the fibre of our lives yet we spend more money on weapons than on ensuring treatment and support of millions infected by HIV."

Mandela said the step to beating poverty was to ensure trade justice, eradicate debt to poor countries and deliver more aid.

Addressing the crowds, Mandela said: "Sometime it falls upon a generation to be great. You can be that great generation. Let your greatness blossom."

Congress of SA Trade Union Cosatu secretary general Zwelinzima Vavi introduced Mandela on to the stage, saying he was the son of Africa.

Vavi chanted "down with poverty down with HIV/Aids".

When Mandela slowly walked on to the stage the crowd were ecstatic, singing his name and repeating the word "Tata".

The Johannesburg Emergency Services and Johannesburg Metro Police Department said the event had gone off smoothly, and there were no incidents to report.

The roads in Newtown would remain barricaded around the venue until midnight although the festival officially ended at 7.30pm.

The concert, organised by Global Call to Action Against Poverty (GCAAP), is one of 10 international music concerts being held towards eliminating poverty and has been dubbed the biggest music event on earth.

It is estimated that more than 5-million people will be tuning in to watch the concert, just a few days before the G8 meeting of wealthy countries takes place in Scotland, with African aid issues the focus.

Overseas concerts kick off
"Ladies and gentlemen, it's two o'clock. Welcome to the greatest rock concert in the world." And thus, a few minutes after 2pm, Live8 began simultaneously at venues in London, Paris, Rome and Berlin.

Backstage, Bob Geldof said:" Everything that's rock 'n' roll is ever meant to be is happening now." He admitted that he only finally relaxed once the concert got underway. "There's nothing more to do now -- it's either crap or it's great and so far it's great," he told reporters a couple of hours into the blockbusting event.

First off was Paul McCartney who opened proceedings in Hyde Park with a rendition of Sergeant Pepper's Lonely Hearts Club Band (opening line, "It was 20 years ago today"), backed by musicians dressed in the iconic Sgt Pepper brightly coloured uniforms. Bono and U2 then took over, performing It's a Beautiful Day with lyrics especially customised for the event. Overhead, grey clouds gathered, but the crowd greeted the performers enthusiastically.

Following U2 were Coldplay, who opened with In My Place. Among the spectators were Chris Martin's wife, Gwyneth Paltrow and their daughter Apple. Richard Ashcroft sang his best known song, Bitter Sweet Symphony, backed by Coldplay. Martin sneaked in a small tribute to Status Quo - who opened Live Aid 20 years previously, singing a few words from their song Rocking All Over The World.

The singer called Bob Geldof "a hero" and thanked the organiser, referring to those who were cynical as 'stupid'. Their brief set ended with Fix You. Elton John performed next, closing with a duet with Pete Doherty. The two sang Children of the Revolution.

Geldof then made a brief appearance, to introduce Bill Gates as "the greatest philanthropist of our age." Gates -- the richest man in the world - and his wife Melinda have given $5-billion towards relieving poverty. Gates paid tribute to Geldof and the event's other organisers. "I believe that if you show people the problems and you show them the solutions they will be moved to act," he said.

"I have learned that success depends on knowing what works and bringing resources to the problem. We know what to do. The generosity we are asking for can save millions of lives. Some day in the future all people no matter where they are born will be able to lead a healthy life."

Dido was up next. The North Londoner sang White Flag, and then was joined on stage by Sengalese singer Youssou N'Dour to sing her breakthrough hit, Thank You. The two then performed N'Dour's 1994 smash hit Seven Seconds.

Both singers will be playing later at the Eden Project in Cornwall, where over 4 000 people are watching some of Africa's best musicians. Acts on the bill there include Thomas Mapfumo from Zimbabwe and his group the Blacks Unlimited, dynamic female vocalist Maryam Mursal from Somalia, and Senegalese hip hop group Daara J.

Eden's organiser Peter Gabriel spoke earlier of his 'disappointment' that Geldof could not have made more space for black artists on the bill at Hyde Park. "I am very happy that we are here today," he said. "It was important that there was the opportunity for African voices to be heard." Guest presenters at the Cornwall event include Angelina Jolie.

Eden's chief executive Tim Smit said: "What is so exciting about hosting this is that what has been created is a cultural palette and people can get a chance to hear a wide range of sounds of Africa. It is very moving and emotional and I hope it catches the mood of the time."

At Hyde Park, Stereophonics followed Dido, and then Ricky Gervais introduced REM. Gervais reprised his famous dance routine from BBC TV series The Office, for "the first and last time only" to the delight of the crowd.

Thousands of people gathered in city centres in Manchester, Wrexham, Cardiff, Birmingham, Liverpool, Hull, Leeds, Gateshead, Bournemouth, Plymouth, Belfast, Inverness and the Channel Islands where screens had been erected to allow people to watch the event free of charge.

Ms Dynamite was followed by Keane, who played Everybody's Changing and Somewhere Only We Know, to roars of approval.

Razorlight frontman Johnny Borrell chatted backstage before his band's set. "I'm not nervous," he told reporters. "I can't wait to get out there. It's great to be here, taking part in something that needs to be done," he said. Borrell is too young to remember the original Live Aid concert of 1985.

"This is not about what happened 20 years ago," he said, "This is about today. My message to the G8 leaders is that this is their chance to make a lot of difference in the world and to come back fulfilling their promises rather than coming back with empty promises. This is their chance to show the world politics is not just showbusiness for ugly people."

At 5pm Bob Geldof came on stage to announce that over three billion people were watching the event. Over in Philadelphia, events were just beginning, with Will Smith on stage to open the US's Live8 concert. The actor and singer introduced live link-ups with the crowds in Berlin, Paris and Canada.

He spoke of a Declaration of 'Interdependence' and urged the crowds to help end world poverty. "Every three seconds, somebody's son, somebodys' daughter, somebody's future is gone. Dead" he said. "With a stroke of a pen eight men can make a difference and end the misery of millions of people."

Geldof returned to the stage in London, this time to perform. "I know it's cheeky, but I couldn't resist playing on this stage," he told the crowd. He sang a powerful version of the Boomtown Rats' hit single, I Don't Like Mondays. "Thanks for letting me do that," he said, leaving the stage to huge cheers.

The Live 8 Concerts will run for 19 hours around the world. The day's final note of music will come from Canadian concert venue Molson Park, Barrie, at 1am tomorrow (British Standard Time); the first concert kicked off this morning in Tokyo at 6am and finished 2pm.

In the US, Philadelphia's Live 8 concert at the Benjamin Franklin Parkway will feature Live8 performers from 5pm until 11pm. Russia's Live8 Concert in Red Square, Moscow runs from 5pm to 8.30pm, while South Africa's concert at Mary Fitzgerald Square, Newtown, Johannesburg, began at 11.45am and will close at 6.30pm.

The world music gig at Cornwall's Eden Project opened an hour before Hyde Park, and will run until at 11pm.

Billions of television viewers around the world are expected to watch today's concerts, with other gigs taking place in Philadelphia, Tokyo, Berlin, Paris, Rome, Johannesburg, Moscow, Barrie (Canada) and the Eden Project in Cornwall. The Hyde Park concert is being broadcast to 85% of the world's population.

The fans in Hyde Park will see a lineup including Madonna, Coldplay, Sir Elton John, Joss Stone, Robbie Williams and U2. Special guest presenters are to include Brad Pitt -- who will be introducing Annie Lennox, David Beckham, introducing Robbie Williams, Ricky Gervais, and Little Britain stars Matt Lucas and David Walliams. Kofi Annan, Cat Deeley, Davina McCall, Chris Evans, Harvey Weinstein and the BBC's political editor Andrew Marr were among the onlookers, while Jonathan Ross was introducing the live television coverage.

The former Beatle will close proceedings with The Long and Winding Road, urging people to travel to Edinburgh for the Long Walk To Justice. Surprise guests were also expected to appear on stage, with George Michael and Sir Mick Jagger rumoured to be among those participating in the grand finale.

The aim of the concerts is to raise awareness of poverty in developing nations in the run-up to the G8 summit, which takes place in Gleneagles on July 6.

"This is without doubt a moment in history where ordinary people can grasp the chance to achieve something truly monumental and demand from the eight world leaders at G8 an end to poverty," the event's organiser, Bob Geldof, said.

"The G8 leaders have it within their power to alter history. They will only have the will to do so if tens of thousands of people show them that enough is enough. By doubling aid, fully cancelling debt, and delivering trade justice for Africa, the G8 could change the future for millions of men, women and children." - Sapa, Guardian Unlimited