World climate talks wound on into the night on Thursday, amid signs of some progress towards bringing the world's major carbon emitters into a deal on tackling global warming.

Facing a coalition of European and developing countries, the United States moved towards a European proposal of a "roadmap" leading to a new pact on carbon emissions.

But the shift fell short of Europe's demands -- and in a high stakes game of poker, China and India had still to declare their hand.

True to the gruelling traditions of climate negotiations, wrangling was likely to continue long after the scheduled close late Friday and well into Saturday.

Chris Huhne, Britain's minister for energy and climate change, declared the United States was giving ground in the face of a united call from two-thirds of the world's nations.

"I think the US is reflecting the pressure that's been brought to bear and is continuing to be brought to bear on many of the other members here who have yet to agree," he said.

"We are making progress, we're not there yet."

Delegates also saw movement on designing a "Green Climate Fund" that by 2020 would catalyse up to 100 billion dollars a year in aid to poor countries exposed to worsening drought, flood, storms and rising seas.

The 12-day talks are the annual get-together of the UN Framework Convention on Climate Change (UNFCCC), a child of the 1992 Rio Summit.

The main source of climate-altering greenhouse gases is cheap and plentiful fossil fuels, which are vital for the world's economy.

As a result, the forum is struggling to make headway, even as scientists say only a few years are left before emissions must peak and then go swiftly into reverse.

Highly complex, the Durban talks hinge on the future of the Kyoto Protocol, the UNFCCC's cornerstone achievement.

Kyoto is the only treaty that stipulates legally-binding curbs on greenhouse-gas emissions, although critics say its format is deeply flawed.

Its constraints only apply to rich countries that have ratified it, thus excluding the United States, which abandoned the Protocol in 2001. Nor does it concern developing countries, on the grounds of their relative poverty.

For these countries Kyoto has iconic value, representing rich countries' historic responsibility for climate change.

But without fresh pledges, the treaty could be left in limbo at the end of 2012.

Canada, Russia and Japan have refused to renew their Kyoto vows beyond this date, given that emerging giants and the United States, which account for the vast majority of greenhouse-gas emissions, have no legal binds.

Europe has promised to endorse a second round of pledges, but only if big emitters, led by China and the United States, back a "roadmap" leading to a new, legally binding treaty for everyone.

US chief delegate Todd Stern found himself in the crossfire of developing countries and an angry US campaigner barracked him at the start of his speech at the UNFCCC plenary before she was led out of the room.

At a press conference afterwards, he insisted that the United States was not blocking progress and -- in an apparent shift in tone -- said he backed the concept of a roadmap.

"If we get the kind of roadmap that countries have called for -- the EU has called for, that the US supports -- for preparing for and negotiating a future regime... we are strongly committed to a promptly starting process to move forward on that," he said.

Clearly eager to avoid misinterpretion, the US delegation later issued a statement spelling out that Stern had not said he supported a "legally binding" agreement, a key part of the EU roadmap.

Several European ministers stood alongside counterparts from developing countries to emphasise what Huhne said was overwhelming support.

"We calculate that 120 of the 193 countries represented here want what we are standing up for today," he said.