BONN, Germany (AP) - A deal can be reached to bring a global warming treaty into effect even without the United States, the chairman of negotiations said Wednesday after U.S. officials reiterated that they will not change their minds about rejecting the Kyoto accord.

Environmentalists, meanwhile, complained that new demands in the latest talks were eviscerating the global warming pact.

Jan Pronk, the Dutch environment minister, admitted his hopes for the 1997 Kyoto Protocol took a dive after the United States - the world's biggest emitter of greenhouse gases - abandoned the agreement in March.

But nations appear committed to reaching agreement at a conference of 178 countries on rules for cutting emissions, he said. A deal here would revive hopes of getting enough countries to ratify Kyoto to bring it into effect.

``I have the impression it is possible to reach a result,'' he said. ``More and more I am hearing discussions that countries want to reach an agreement. It may be a different kind of agreement than what countries did have in mind ... but an agreement.''

Pronk refused to say what shape a long-sought agreement might take. But he did say progress has been made during three days of technical discussions so far at the conference, which he chairs.

Environment ministers join the talks Thursday, launching what Pronk hopes will be the final phase of negotiations on a package of measures for implementing the Kyoto agreement. The protocol requires industrialized countries to cut greenhouse emissions an average of 5.2 percent from 1990 levels by 2012.

About 30 countries have ratified the pact so far, but it requires backing by 55 countries representing 55 percent of the industrialized world's emissions.

Pronk admitted the survival of Kyoto hangs in the balance of the talks. If no agreement is reached by the end of the Bonn talks, the treaty wouldn't be dead but ``it would be utterly sick,'' he said.

Although the United States has pulled out of the treaty, it is participating in the Bonn talks, raising hopes among some that Washington wants to leave options open for joining in the future.

But a U.S. official at the talks brushed away hopes that Washington would one day rejoin the protocol as ``wishful thinking.''

``That we'll come back to the Kyoto Protocol after our policy review is quite unlikely. It's just not going to happen,'' the official said on condition of anonymity.

President Bush argues that the treaty is flawed and that its binding emissions cuts would harm the American economy.

With the United States standing aside, Japan's adoption of the deal has become crucial. Japan, Canada and Australia are pressing demands for wider leeway to seek credit toward emissions for forests that absorb carbon dioxide.

Those demands have angered environmental groups.

``In essence, they're killing the Kyoto Protocol behind the scenes,'' said Jennifer Morgan of the Worldwide Fund for Nature, accusing the countries of taking ``hard-line, unconstructive positions.''

European Union countries want strict limits on counting the beneficial effects of forests and soil. German Environment Minister Juergen Trittin said Wednesday that the EU has ``some very critical concerns'' about the three-nation proposal.

Japanese Prime Minister Junichiro Koizumi rattled European leaders last week by suggesting that, after the U.S. pullout, an agreement may not be possible before the fall. But his environment minister, Yuriko Kawaguchi, has said Japan would ``do its utmost'' to help bring the treaty into force by next year.