The Group of Eight rich nations will seek to convince a sceptical Africa on Monday that it is living up to promises to double aid to the world's poorest continent.

Underlining the importance of the issue, the G8 has invited seven African leaders to join the opening day of its annual summit, taking place at a plush hotel on the northern Japanese island of Hokkaido.

Climate change, record oil prices and a deteriorating global economy add up to a crowded agenda for the three-day meeting, but U.S. President George W. Bush said he particularly wanted to hold fellow leaders to account for their African aid pledges.

"We'll be very constructive in the dialogue when it comes to the environment - I care about the environment - but today there's too much suffering on the continent of Africa, and now's the time for the comfortable nations to step up and do something about it," Bush, banging the lectern for emphasis, said on Sunday at a news conference with Japanese Prime Minister Yasuo Fukuda.

At its 2005 summit in Gleneagles, Scotland, the G8 agreed to double aid to Africa by 2010 as part of a wider drive to alleviate global poverty.

But a report last month by the Africa Progress Panel, which was set up to monitor implementation of the Gleneagles commitments, said that under current spending plans the G8 will fall $40 billion (20 billion pounds) short of its target.

Soaring food and oil prices have deepened Africa's plight, but Japan vigorously rebutted a media report that the G8 was backsliding.

"Frankly speaking, we are a little annoyed by the recent press report," Foreign Ministry press spokesman Kazuo Kodama said. "That is completely false and unfounded."

LOSING TRACTION?

This year marks the half-way point in a drive to reach by 2015 eight Millennium Development Goals (MDGs) set by the U.N. General Assembly in September 2000 to reduce world poverty.

Kodama acknowledged that Africa was well behind target in the area of health, but added, "G8 leaders will certainly deliver a strong and concrete message to help African countries to achieve MDGs."

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."