Thousands of protesters have lined the banks of London's Thames in a major demonstration against global poverty.
Midge Ure and Annie Lennox are backing the demonstration
At 1430 GMT, campaigners on the riverbank near the Houses of Parliament began "three minutes of noise" using whistles, alarms and other devices.
Many protesters wore white, a reference to the 2005 Make Poverty History "White Band" campaign.
The event was held to remind leaders of pledges on poverty ahead of the G8 summit in Germany next week.
Rock stars Midge Ure and Annie Lennox have lent their support to the protest, called the World Can't Wait and organised by a coalition of 90 organisations.
It was held as police battled hundreds of protesters at an anti-globalisation march in Rostock, Germany, 25km (16 miles) away from where next week's G8 summit will be held.
The London demonstration was co-ordinated from a barge on the river with banners reading "We Can't Wait" and "Your Voices Against Poverty" and carrying a choir and African drummers.
Organisers said upwards of 10,000 people attended the protest but police were unable to confirm this figure.
Campaigners say leaders have not delivered on promises to tackle poverty made at the G8 meeting of world economic powers at Gleneagles in 2005.
Kumi Naidoo, from the Global Call to Action Against Poverty said: "There's lots of talk about Tony Blair's legacy, and this summit offers a golden opportunity for him to really leave a mark.
"In 2005 the British public gave the government a huge mandate to fight poverty. People across Africa are still waiting for the G8 to deliver."
Midge Ure told the BBC News website: "It's a gentle reminder that we are here again two years down the line with commitments that have not been fulfilled."
He added: "I went to Sierra Leone last year. It's one of the poorest countries to be born in. One in four children don't make it to the age of five.
"There's no free health care. I expected to see extreme poverty but I didn't expect to see emaciated babies. It's obscene."
He said he was hopeful that the future prime minister, Gordon Brown, would push forward steps to tackle world poverty.
He took part in a debate at the event, while Annie Lennox was to address the crowds from a boat on the Thames.
Among the other events on Saturday was a "blow the whistle" service organised by church groups at Methodist Central Hall.
The service was part of a campaign by Christian organisations to see how far countries have progressed towards the goal set in 2000, of halving poverty by 2015.
In 2005, the G8 pledged $50bn more aid, debt cancellation for up to 42 countries and access to affordable treatment for people with HIV/Aids by 2010.
Bob Geldof organised a number of Live 8 concerts across the world to try to get the G8 to take action on poverty.
Campaigners say rich nations have failed to deliver increased aid and debt cancellation.
A Downing Street spokeswoman said progress had been made since Gleneagles.
Among other achievements she said global aid had increased from $79.4bn to $103.9bn this year, 22 countries had been given 100% debt relief and $1bn had been raised for new and basic vaccines.