At least one delegate, though, was pessimistic over prospects for any breakthroughs in time for the July 7-9 summit in Hokkaido, northern Japan, where G8 leaders will be joined by big emerging economies such as China for climate change talks.

"I think it is difficult. We have not enough time," Mexican Environment Minister Juan Rafael Elvira Quesada told reporters. "But climate change is not waiting for any of us."

G8 leaders agreed last year in Germany to consider seriously a goal to halve emissions by 2050, a proposal favoured by Germany, France, Britain, Italy, Japan and Canada.

About 190 nations have agreed to negotiate by the end of 2009 a successor treaty to the Kyoto pact, which binds 37 advanced nations to cut emissions by an average of 5 percent below 1990 levels by 2008-12.

But wide gaps exist within the G8 and between rich and poorer nations over how to share the burden for fighting climate change, blamed for droughts, rising seas and more intense storms.

TARGETS, FUNDS, TECHNOLOGY

Developing countries are putting priority on growth and balking at targets, while complaining that the United States, which together with China is a top emitter, is not doing enough.

Indonesia's deputy environment minister told reporters that G8 countries needed to set their own mid-term targets before asking developing countries make commitments. "First, they should do a mid-term target," said Masnellyarti Hilman.

"Developed countries should take the lead and give their commitment to give transfer of technology, finances and capacity building to developing countries," she added.

South Africa wants the G8 to set ambitious mid-term targets to cut emissions by 25-40 percent below 1990 levels by 2020, and provide more funds to help developing nations adapt to climate change and limit emissions, Environment Minister Marthinus van Schalkwyk said in a prepared statement.

"As developing countries, we are looking at the G8 for leadership. This is a key ingredient towards building trust," he said.

The European Union has said the bloc aims to reduce greenhouse gas emissions by at least 20 percent by 2020 from 1990 levels, but the United States says only that it will halt the growth of its emissions by 2025 and expectations are low for bold moves until a new president takes office in January 2009.

Japan, seeking to show leadership as G8 summit host, urged its rich country colleagues to set bold national targets to cut greenhouse gas emissions by well over 50 percent by 2050.

"It is also important for global emissions to peak out in the next 10 to 20 years to reach the long-term target, and I hope that a shared view will be come out of the (G8) summit," Japanese Environment Minister Ichiro Kamoshita added.

Japan is currently debating its own national target, and domestic media have said it would announce in June a goal of reducing emissions by 60-80 percent by mid-century.

Big emerging economies also want rich countries to help finance the clean energy technologies they need to cut emissions.

Japan has pledged to pay $10 billion over five years to support developing countries' fight against climate change and intends to create a new multilateral fund with the United States and Britain.

Now Washington and Tokyo want other donors to take part too.

Mexico is pitching its own proposal for a "Green Fund", while the World Bank on Friday said that 40 developing and industrial nations would create two new investment funds to provide financing for developing countries to fight climate change.

But the Bank specified no amounts and did not clarify the relationship to existing funding mechanisms.