Charity group Oxfam said an early version of a statement to be issued after this week's meeting would set up accountability mechanisms for subsequent summits, particularly in health, a step that it said was welcome.
But it said the G8 - the United States, Japan, France, Britain, Germany, Canada, Italy and Russia - was making no major new financial commitments and was trying to water down a pledge at last year's summit in Germany to meet the Gleneagles goals.
"The communique draft represents a significant climbdown from the German G8 on the reiteration and reaffirmation of Gleneagles promises of $25 billion annually for Africa by 2010 and $50 billion annually overall by 2010," Oxfam said.
With grain prices having doubled since January 2006, Africa needs more help, not less, activists say.
A preliminary World Bank study released last week estimated that up to 105 million people could drop below the poverty line due to rising food prices, including 30 million in Africa.
In Liberia, the cost of food for a typical household jumped by 25 percent in January alone, increasing the poverty rate to over 70 percent from 64 percent, the study found.
"I cannot stand the idea that a food crisis born out of high energy prices and increasing global prosperity is starving the super-poor in Africa," rock star Bob Geldof, who will lobby G8 leaders at the summit, said in a statement last week.
CLIMATE CHANGE
The G8 holds talks on Monday with the leaders of Algeria, Ethiopia, Ghana, Nigeria, Senegal, South Africa and Tanzania.
On Tuesday they turn to economic problems, the traditional stuff of the summit, before sitting down with another clutch of non-member countries on Wednesday to thrash out the contentious issue of global warming.
Those invited include China and India, two fast-growing economies that are pumping out more and more greenhouse gases, and Bush played down hopes of making headway this week unless Beijing and New Delhi changed tack and agree to cap emissions.
Deep divisions within the G8 as well as between rich and poor nations have raised doubts about the chances for progress beyond last year's summit, where the G8 agreed to "seriously consider" a global goal of halving greenhouse gas emissions by 2050.
"I'll be constructive. I've always advocated that there needs to be a common understanding and that starts with a goal," Bush said. "And I also am realistic enough to tell you that if China and India don't share that same aspiration, then we're not going to solve the problem."
