"We have a clear problem with our American friends," he told AFP on the sidelines of a closed-door meeting aimed at laying the groundwork for a political agreement at next month's UN conference on global warming.

Environment ministers from 44 key countries took part in the two-day talks.

The world's industrialised countries signed in 2007 the Bali declaration, vowing to reduce carbon emissions by 25 to 40 percent by 2020, Borloo said.

"They (the Americans) are between 0 and -4 percent. We can understand that they need flexibility and we need to accept that, but the world's greatest power, which pollutes the most per capita, has to commit more" to reducing its emissions, Borloo said.

The minister presented his "climate-justice" plan while in Copenhagen, which UN climate chief Yvo de Boer said was "interesting" and "well received by the African delegates."

The French plan, which has not yet been made public, pinpoints the efforts that have to be made to attempt to reverse the effects of climate change.

It has been sent to about 20 key countries.

With three weeks left to the Copenhagen summit, "uncertainties remain because of discrepancies between countries," a source close to Danish Prime Minister Lars Loekke Rasmussen said.

The meeting will be "like a family dinner where anything can happen," Borloo said, adding "it could be the best of dinners but could also go wrong because of misunderstandings," he said.

The December 7-18 talks in Copenhagen are aimed at reaching a post-2012 deal for slashing greenhouse-gas emissions and easing the impact of likely droughts, floods, storms and rising seas unleashed by disrupted weather systems.

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