BALI, Indonesia - The United States will come up with its own plan to cut global-warming gases by mid-2008, and won't commit to mandatory caps at the United Nations' climate conference here, the chief U.S. negotiator said Saturday.

"We're not ready to do that here,'' said Harlan Watson, the State Department's senior climate negotiator and special representative. "We're working on that, what our domestic contribution would be, and again we expect that sometime before the end of the Major Economies process.''

That process of U.S.-led talks was inaugurated last September by President George W. Bush, who invited 16 other major economies such as the Europeans, Japan, China and India, to Washington to discuss a future international program of cutbacks in carbon dioxide and other emissions blamed for global warming.

Environmentalists accuse the Bush administration of using those parallel talks to subvert the long-running UN negotiations and the spirit of the binding Kyoto Protocol, which requires 36 industrial countries to make relatively modest cuts in "greenhouse'' gases.

The United States is the only major industrial country to have rejected Kyoto and its obligatory targets. The U.S. leadership instead favours a more voluntary approach, in which individual countries determine what they can contribute to a global effort, without taking on obligations under the UN climate treaty.

Watson's comments reaffirmed that the Bush administration views its own talks as the main event in discussions over climate change.

The European Union, on the other hand, has committed to binding emissions reductions of 20 per cent by 2020. Midway through the two-week Bali conference, many of the more than 180 assembled countries were demanding such firm commitments from Washington as well, as the world talks about a framework to follow Kyoto when it expires in 2012.

"It would be useful for Annex I, non-Kyoto countries'' -- code for the U.S. -- "to indicate what level of effort'' they'll make, said M.J. Mace, a delegate from the Pacific country of Micronesia, whose islands are threatened by seas rising from global warming.

The conference's main negotiating text, tabled for debate on Saturday and obtained by The Associated Press, mentions targets, but in a nonbinding way.

Its preamble notes the widely accepted view that industrial countries' emissions should be cut by 25-40 per cent below 1990 levels by 2020 to help head off climate change's worst impacts -- expanding oceans, spreading droughts, dying species, extreme weather and other effects.

Even mentioning such numbers in the conference's key document may set off renewed debate next week, when environment ministers and other ranking leaders join the talks, which are meant to launch a two-year negotiation for a post-Kyoto deal.

Meanwhile, Climate Action Network Canada says a leaked federal document shows Canadian negotiators in Bali are under explicit instruction to undermine a fundamental principle of the Kyoto Protocol.

The alliance of environmental groups says the move is guaranteed to derail momentum as the Bali negotiations enter their critical final week.

"The leaked instructions direct Canadian negotiators to demand that poorer nations accept the same binding absolute emission reduction targets as developed nations,'' the alliance said in an e-mail to The Canadian Press.

It said the Kyoto Protocol is built on the recognition that industrialized countries are largely responsible for the problem of climate change, and must take the lead in tackling it.

"Although countries such as China and India need to significantly slow their emissions growth, they should not, in the near term, be subject to the absolute emission reduction targets that are appropriate for industrialized countries. Canada's per-capita emissions and wealth are about 10 times higher than India's and five times higher than China's,'' it noted.

Delegates here made progress in the first week on such secondary matters as establishing a system for compensating tropical forest countries for reducing deforestation, a major source of carbon emissions. They're expected to approve work on measuring forest cover, emissions and related factors.

"I've observed a strong willingness on the part of countries to get a successful outcome in Bali,'' the UN climate chief, Yvo de Boer, told reporters in assessing the first week.

American negotiator Watson said the Bush administration is planning probably four more meetings in the major economies series before a "leaders' meeting'' in mid-2008 presents a final outcome.

Asked how the U.S.-organized process would complement the UN treaty talks, he said, "We think if we could get agreement among these 17 economies, or a good portion of them anyway, that would certainly contribute to that discussion in terms of any sort of interim goals or targets that might be discussed.''

But he acknowledged it remained unclear how the two "tracks'' would merge.