Brice Lalonde, the French ambassador for climate change, noted a shift in the US position, which he said had previously been "a bit lagging" in failing to set goals to reduce its overall emissions of greenhouse gases.

"And now we are seeing that the United States is discussing the matter," Lalonde said at a news briefing. "We welcome this move. Of course we are waiting for the next step, which would be that the United States will also have a goal in reducing its greenhouse gases, joining in that way all developed countries."

The US-hosted meeting in Honolulu gathered delegates from 17 so-called major economies - the Group of Eight industrialized nations plus fast-developing China and India along with Australia, Brazil, Indonesia, Mexico, South Africa, South Korea and the European Union - to work together to spur UN negotiations on climate change.

The goal is to craft an international agreement to succeed the Kyoto Protocol, which expires in 2012. To make sure the new agreement is ready in time, a new pact must be ready by 2009.

The United States, by most counts the world's biggest emitter of carbon dioxide, rejects Kyoto on the ground that it unfairly exempts China and India and says any new agreement must include all countries.

The first meeting of major economies, convened in Washington in September, found some delegates complaining that the United States was isolated for its stand against Kyoto and that the US-led process had the potential to distract from rather than contribute to the UN negotiations.

James Connaugton, head of the White House Council on Environmental Quality, sounded encouraged by the frank, hard-working and civilized tone of this week's talks.

"You're not seeing the questioning, the concerns, you're not seeing that," Connaughton said in an interview on the final day of the closed-door sessions.

"We're now getting into some very specific areas on some issues that are quite sensitive and we are working hard to more clearly understand the different perspectives of different delegations and look for common ground."

"We had a very constructive debate," said Matthias Machnig of Germany's Ministry for the Environment. "It's very important to have an international regime of mandatory targets based under the umbrella of the United Nations and hopefully we made a step forward here to come to real agreement in 2009."