Exasperated green groups walked out of faltering UN climate talks in Warsaw on Thursday as rich and poor nations bickered about who must do what to curb planet warming.

Negotiators were at loggerheads on the penultimate day of talks over divvying up responsibility for cutting greenhouse-gas emissions and scaling up aid to poor states vulnerable to climate change effects.

In a dramatic flourish, six environment and development groups walked out, saying the annual round of talks had delivered little more than hot air since opening on November 11.

"The Warsaw climate conference, which should have been an important step in the just transition to a sustainable future, is on track to deliver virtually nothing," said a statement announcing the groups' decision to "voluntarily withdraw".

The signatories are Greenpeace, WWF, Oxfam, ActionAid, the International Trade Union Confederation and Friends of the Earth.

They claimed more than 800 UN-accredited observers were part of the mass protest.

The groups pointed the finger at Poland for its "endorsement" of a global coal summit held in the same city and at the same time as the climate talks. They also singled out Japan for slashing its carbon emissions goal, and Australia for its decision to scrap a carbon tax on high emitters.

"Governments here have delivered a slap in the face to those suffering as a result of dangerous climate change," said Greenpeace executive director Kumi Naidoo.

Non-governmental organisations attend the talks as observers and advisors. Decision-making is reserved for UN member states.

On Wednesday, UN chief Ban Ki-moon had urged nations to "much bolder" action to stave off an existential peril for the Earth.

Gathering more than 190 nations, the talks are meant to pave the way to a pact by the end of 2015 to limit warming to 2.0 degrees Celsius (3.6 degrees Fahrenheit) over pre-industrial levels by taming carbon gases emitted by burning coal, oil and gas.

On current emissions trends, scientists warn the Earth could face warming of 4.0 C or higher -- a recipe for catastrophic storms, droughts, floods and a land-gobbling sea-level rise.

Roadmap for 2015?

Delegates said there have been few advances in crafting a roadmap for arriving at a historic climate deal in Paris, now only two years away.

"There are still things that are very important to us where we do not see enough progress, for instance a clear timeline, and key elements of the 2015 agreement," European climate commissioner Connie Hedegaard said after another round of all-night talks.

"We are not moving forward in our discussions."

Developing countries want wealthy nations to shoulder a bigger share of emissions cuts to make up for a long history of fossil-fuel combustion.

The West, however, insists that emerging economies must do their fair share.

It argues that tomorrow's warming problem will mainly come from today's developing giants, which are voraciously burning indigenous reserves of coal.

China is now the world's biggest emitter of CO2, with India in fourth place after the United States and Europe.

Developing giant Brazil's Foreign Minister Luiz Alberto Figueiredo Machado said Thursday the new deal may have "different kinds of obligations for different countries or different groups of countries".

China, for its part, stressed that inequalities between industrialised and developing nations "will persist after 2020".

But US climate envoy Todd Stern said a deal with obligations distinguishing between groups on the basis of an outdated rich-poor country divide "will not work".

Work on a 2015 deal would only be successful "if we leave ideology at the door", said Stern.

Another quarrel is over money.

Developing nations are challenging wealthy countries to show how they intend to honour a 2009 pledge to muster up to $100 billion (74 billion euros) by 2020, up from $10 billion a year from 2010 to 2012.

Still struggling with an economic crisis, however, the developed world is wary of unveiling a detailed plan at this stage, or pledging any new short-term figures.

The money crunch also lies at the heart of another issue bedevilling the talks: demands by developing countries for a mechanism to help them deal with future losses from climate impacts they say are too late to avoid.

Rich nations fear this amounts to signing a blank cheque for never-ending liability.