Copenhagen deal should have immediate effect - Obama

US president Barack Obama said on Tuesday that climate talks in Copenhagen next month should fix a new deal which has "immediate operational effect", even if an original goal of a legally binding pact is out of reach.

Obama's remarks came after a meeting with his Chinese counterpart Hu Jintao, who has pushed for a strong outcome at Copenhagen and refused to back a proposal to rekindle stalled negotiations by aiming for a scaled-down political deal.

 Together the United States and China account for 40% of world emissions, so their support is vital to any agreement.

"Our aim there ... is not a partial accord or a political declaration but rather an accord that covers all of the issues in the negotiations and one that has immediate operational effect," Obama said of the Copenhagen talks.

The international community had set a December deadline to agree a framework to tackle global warming from 2013, but a rift has opened between developed and developing nations over who should cut emissions, by how much, and who should pay for it.

Danish prime minister Lars Lokke Rasmussen, in a last-ditch bid to dispel growing gloom about the talks he will host from Dec. 7-18, has proposed a delay in a legally binding pact until 2010 or later and aim for a political deal first.

Obama, who advocates strong action on climate change but is struggling to get legislation mandating domestic action through the US Congress, backed that plan.

But his call on Tuesday for a wide-ranging agreement that would take effect immediately suggests he is keen to walk away from the talks with more than just a piece of paper.

China has said only that it is "studying" the proposal.

Beijing has invested large amounts of diplomatic capital in reaching a new deal. Hu earlier this year unveiled the country's first pledge to curb carbon emissions at a UN summit.

And some in China, and other developing nations, are suspicious that the push for a delay is a rich nation ploy to defer facing costly responsibilities for decades of emissions.

After his talks with Obama, Hu said the two sides had committed to working more closely on tackling global warming and called for a "positive outcome" from the talks, although experts admit that time has essentially run out to fix a legal deal.

Hu emphasised a long-standing global agreement that states countries have a shared responsibility for tackling warming but should take on different levels of commitment depending on their economic and social situation.

Obama said the world's top two carbon emitters had committed to take "significant" action to mitigate their output of carbon dioxide, and agreed to cooperate in areas including renewable energy, cleaner coal and electric vehicles.