TOYAKO, Japan: US President George W. Bush's last Group of Eight summit only inched forward the fight against climate change but drew the battle lines more sharply than ever between rich and poor nations.

The G8 major industrial powers agreed at a three-day summit in northern Japan to cut carbon emissions blamed for global warming by at least half by 2050, the strongest language yet signed by Bush.

But developing nations shot back by insisting that rich countries were most to blame for climate change and needed to commit to bigger and quicker emissions cuts.

Australian Prime Minister Kevin Rudd, who took part in an expanded 16-nation summit on climate change on Wednesday here in the secluded mountain resort of Toyako, said that it failed to reach a needed consensus.

"The challenge will be great and there is no great breakthrough at this particular meeting," Rudd said.

Some leaders who were not invited to the elite summit were disappointed at the outcome.

Spanish Prime Minister Jose Luis Rodriguez Zapatero said the climate deal was "another step but not definitive," while his Dutch counterpart Jan Peter Balkenende said the results "were not those that were expected."

Zapatero also faulted the G8 summit for not doing more to bring down soaring food prices, which have caused riots in parts of the developing world.

The summit of the G8, Britain, Canada, France, Germany, Italy, Japan, Russia and the United States, was the last for Bush, whose first act on taking office in 2001 was to pull the world's biggest polluter out of the Kyoto Protocol on climate change.

The Bush administration has since clashed bitterly with the European Union in UN-led negotiations that have a December 2009 deadline to come up with a treaty for the period after Kyoto's obligations expire in 2012.

But in a change in tone, European leaders in the G8 all hailed the Toyako summit as a step forward and joined the United States in calling for more action by developing countries.

Environmentalists said the Europeans saw no point in fighting with Bush as both major candidates to succeed him, Barack Obama and John McCain, have pledged to take stronger action against climate change.

Greenpeace campaigner Daniel Mittler said that Europeans also did not want an ugly brawl while in Japan, which sought desperately to show leadership on the world stage through the G8 summit.

But Mittler said that the Europeans, the champions of the Kyoto Protocol, have widened the chasm with developing nations by aligning with Bush.

"I can't understand why the Europeans are taking the diplomatic niceties as far as they are," he said.

"It's difficult to grasp because of the impact it is having on the relationship with the developing countries."

Paradoxically, one of the biggest outcomes of the G8 meeting is that developing nations put a clear proposal on the table.

Leaders of the so-called Group of Five -- Brazil, China, India, Mexico and South Africa -- said that by 2020 rich nations should cut emissions by 25 to 40 per cent from 1990 levels, and by 80 to 95 percent by 2050.

"What's new here is that we've now got a sense of what the G5 want. So if developed countries want to do something, they now have an open door," said Kim Carstensen, director of the WWF Global Climate Initiative.

The Group of Eight also aired concerns about oil prices, threatened more action on Zimbabwe over its disputed election and set a five-year deadline for rich nations to provide 60 billion dollars to Africa to fight disease.

Andrew Cooper, a professor of political science at the University of Waterloo in Canada, said that while the G8 summit yielded some progress on climate change, it tried to do too much.

"The statement looks like a Christmas tree with lots of lights, lots of attractions," he said.

"The G8 doesn't do justice to the world if it tries to have statements on every top issue of the world."