Oxfam has urged Tony Blair to make the fight against poverty in Africa a priority for his time left in office.
Bob Geldof was speaking two years after the Gleneagles agreement
The charity says donations from rich nations have fallen since the prime minister's Commission for Africa report two years ago sought more aid.
Campaigner Bob Geldof criticised European leaders for losing interest in Africa since the Gleneagles agreement.
The International Development Secretary said the UK was working to ensure G8 donors keep the promises made.
"The German G8 Presidency in 2007 has made development in Africa a top priority which shows continued determination by rich countries to help tackle the issues facing the continent," Hilary Benn added.
Mr Geldof said if wealthy countries broke their promises over Africa it would "kill the poor" on that continent.
"When they put their name, they sign the pride, the honour, and the dignity of their respective countries. You do not break that," he told BBC Radio 4's Today programme.
"You particularly don't break it because the promise of the rich to the poor broken, kills the poor."
European leaders signed an agreement on aid and trade at the G8 summit at Gleneagles two years ago.
Oxfam said Mr Blair's "vision" on aid risked being deeply undermined.
Mr Geldof said Europe was guilty of ignoring the situation in Africa, as the European Union marks its 50th anniversary.
He said: "On our 50th birthday anniversary we are silent about our closest neighbour and where potentially two million people will be killed in one region alone, Darfur.
"What have Europe got to say on our 50th birthday about this? Nothing, absolutely nothing."
Mr Geldof accused China, amongst others, of exploiting Africa's natural resources.
"Into the vacuum of our lack of fulfilment have stepped the Chinese, who do not care about the values of democracy, transparency and accountability, and said 'We'll give you the money so long as we have influence over your resources and your politics'," he said.
Mr Geldof praised the prime minister's international lead on Africa, and said he thought this would be continued by Gordon Brown if he succeeded Mr Blair as prime minister.
The government has said it is committed to spending 0.7% of national wealth on aid by 2013, two years ahead of a UN target.