But Australia has dismissed the idea and the United States -- the world's biggest polluter -- is campaigning to kill off the existing Kyoto treaty let alone extend it.

Both countries have refused to ratify Kyoto which came into effect in February and is aimed at cutting global greenhouse gas emissions by 5 percent below 1990 levels by 2012.

They say the target would mean economic suicide.

"Negotiations of this kind are always very difficult. Our objective is to get an agreement to start negotiations," Dimas told environment reporters, noting the importance of bringing in major developing economies like India and China.

He said phase two of Kyoto should have mandatory emission cut targets for developed nations but allow flexibility for the developing world.

"Bringing the United States on board is very difficult. We have to find a solution to bringing the developing countries on board. We have to have long discussions to find a way that is appropriate for all of these countries," he said.

But he expressed optimism that eventually the United States would commit to a target-based battle against global warming.

Scientists say the world's temperature could rise by more than two degrees Celsius this century, bringing droughts and storms, while melting polar ice caps will raise sea levels and risk the lives of millions. Most agree that the main cause of warming is gasses like carbon dioxide from burning fossil fuels.

As an indication of the opposition Dimas will face, the head of a right-wing Brussels-based think tank said meeting the Kyoto targets would send many major European economies into recession.

"To reduce carbon emissions you have to reduce consumption, and that can only be done by raising prices," Margo Thorning, head of the International Council for Capital Formation, told Reuters in an interview in London.

"It is wrong to put a country on an economic starvation diet. A good outcome in Montreal would be a decision to end Kyoto," she said, echoing the White House line that the answer lay in areas like new technology, clean coal, nuclear energy and carbon capture and sequestration.

The ICCF, the European arm of the car and oil industry-funded American Council for Capital Formation, says meeting Kyoto would cost more than 600,000 jobs in Spain, 300,000 each in Germany and Britain and over 200,000 in Italy.