Yvo de Boer, the U.N.'s top climate official, praised the December 3-14 meeting of 10,000 participants for progress towards a goal of launching formal talks on a long-term climate pact to succeed the U.N.'s Kyoto Protocol.

"But in this process, as in so many, the devil's in the detail," he cautioned in an interview with Reuters at a beach-side conference centre on the Indonesian island.

Governments set up a "special group" to examine options for the planned negotiations meant to bind the United States and developing nations led by China and India more firmly into fighting climate change beyond Kyoto.

The meeting also agreed to study ways to do more to transfer clean technologies, such as solar panels or wind turbines, to developing nations. Such a move is key to greater involvement by developing nations in tackling their climate-warming emissions.

The Kyoto Protocol now binds 36 rich nations to curb emissions of greenhouse gases, mainly from burning fossil fuels, by an average of 5 percent below 1990 levels by 2008-12 in a step to curb droughts, floods, heatwaves and rising seas.

But there was skirmishing about how to share out the burden beyond Kyoto and environmentalists accused Kyoto nations Japan and Canada of expecting China and India to do too much.

Canada said in a submission to the talks that "to be effective, a new international framework must include emission reduction obligations for all the largest emitting economies". It did not mention deeper cuts for rich nations beyond 2012.

And Japan on Monday called on all parties to effectively participate and contribute substantially. A Japanese official said it was "essential" that China and India were involved.

"Canada and Japan are saying nothing about legally binding emission reductions for themselves after 2012," said Steven Guilbeault of environmental group Equiterre. "They are trying to shift the burden to China and India."

NO FORMAL PROPOSALS

Green groups gave Japan a mock award as "Fossil of the Day" -- made daily to the nation accused of holding up the talks.

De Boer played down the environmentalists' objections, saying that all nations were merely laying out ideas. "A marriage contract is not something to discuss on a first date," he said. "No proposals have formally been made."

China and India say that rich nations must take on far deeper cuts in emissions and that they cannot take on caps yet because they need to burn more fossil fuels to end poverty.

The Bali talks are seeking a mandate to widen Kyoto to all nations beyond 2012. Of the world's top-five emitters, only Russia and Japan are part of Kyoto. The United States is outside the pact, while China and India are exempt from curbs.

And de Boer also said the talks should not focus solely on the plan to launch new negotiations. "There's a bit of a risk that countries that are very keen to see negotiations being launched go over the top and focus only on that," he said.

Developing nations were worried that more immediate issues -- such aid to help them cope with droughts, floods and rising seas -- could "be forgotten in all the excitement about the future", he said.

Outside the Bali conference centre on Tuesday, a group of environmentalists gave a mock swimming lesson to delegates, saying that rising seas could swamp low-lying tropical islands such as Bali unless they acted.

"Sea level rise is threatening hundreds of millions of people," they said. "Sink or swim!"