'I have been there and to walk away from it, turn my back, makes me culpable and I cannot do that,' explained Brad Pitt.

Brad Pitt

Brad Pitt is talking about the poverty he witnessed in South Africa.  Now there's a new ad campaign to get everyone in developed countries involved.

It features Brad Pitt and other big name Hollywood stars who have joined Bono's campaign to fight poverty and disease. Bono says the goal is to get the fans to pressure politicians to keep their promises to combat poverty.

'We're not actually asking for their money, we're asking for their voice(s),'  Bono explained.

In September 2000, the United Nations started a campaign that would cut world poverty in half by 2015. Five years later, not much progress has been made.

Bono, Brad Pitt, and Djimon Hounsou, left to right, pose for photos after news conference at which public service announcement for ONE - The Campaign to Make Poverty History was shown

Joining Bono's campaign is MTV's Ian Rowe who says, 'We saw an unbelievable response to the tsunami.  But, as many experts say, there is a silent tsunami happening almost every month throughout parts of Africa and Asia.'

When the leaders of the G8 economic powers meet in July, Bono wants them to firmly commit to reducing poverty throughout the world. He is counting on public pressure to ensure this happens.