The leaders of the world's richest eight nations have pledged to spend $60bn fighting Aids and other killer diseases in Africa.

G8 leaders, who are meeting on the final day of GM Summit 2007 in the German resort of Heiligendamm, also said they would honour aid vows made at a previous meeting held in Gleneagles, Scotland, in 2005.

Half of the $60bn earmarked to fight Aids, malaria and tuberculosis will come from the US.

"We are aware of our responsibilities and will fulfill our obligations," German Chancellor Angela Merkel, hosting G8 leaders, told journalists on Friday morning.

But a number of aid agencies and anti-poverty campaigners said they were disappointed with the deal.

Development, relief and campaigning organisation Oxfam felt the deal contained little new money.

Steve Cockburn, Stop Aids Campaign: "While lives will be saved with more money for Aids, this represents a cap on ambition that will ultimately cost millions more lives."

"I am exasperated," U2 singer and anti-poverty campaigner Bono told Reuters news agency.

"I think it is deliberately the language of obfuscation. It is deliberately misleading."

Bono added: "They have taken language hostage. We wanted numbers but this is burobabble.

"It is not real in any language. We are looking for accountable language and numbers. I might be a rock star but I can count."

Steve Cockburn, of the Stop Aids Campaign, said: "While lives will be saved with more money for Aids, this represents a cap on ambition that will ultimately cost millions more lives."

G8 leaders made a number of ambitious pledges at the Gleneagles summit back in July 2005.

They agreed to wipe the debts of 18 African countries, including Benin, Bolivia, Burkina Faso, Ethiopia, Ghana, Mauritania, Mozambique and Zambia.

The G8 also announced a $50bn aid boost for Africa and pledged universal access to HIV drugs in Africa by 2010.

In other discussions at the Heiligendamm summit, G8 leaders agreed a new deal on climate change.

On Thursday afternoon, Chancellor Merkel said the G8 would aim to at least halve global CO2 emissions by 2050.

The G8 countries are the US, Canada, the UK, France, Germany, Italy, Japan and Russia.