WARSAW (AFP) - UN climate talks were blocked in Warsaw Saturday more than 12 hours after they were to have delivered a roadmap towards a global pact to stave of dangerous global warming.

The belligerent negotiations were to have closed at 5 pm on Friday, but by breakfast time Saturday, diplomats were still shuttling to and fro in a last-ditch bid to find consensus.

"There will be no forcing of decisions against the will of parties," conference president Marcin Korolec of Poland told a brief stock-taking meeting at 6 am - and said it was "premature" to set a time for the closing plenary meeting.

"We will reconvene here in a formal setting at 9 am to address the situation and find a way forward to conclude the conference," he said.

The Warsaw round of the notoriously fractious annual talks have seen rich and poor nations butting heads since November 11 about their respective contributions to the UN-backed goal of limiting average global warming to 2.0 degrees Celsius over pre-industrial levels.

UN nations had agreed to sign a global deal by 2015 to meet this goal with binding targets for all countries to curb climate-altering greenhouse gas emissions. The pact must be inked in Paris in two years' time, and will enter into effect in 2020.

Negotiators from over 190 countries argued in the Polish capital over apportioning targets for carbon emissions cuts between rich and poor states, and over funding for climate-vulnerable countries.

On current emissions trends, scientists warn the Earth could face warming of 4.0 C or higher over pre-industrial levels - a recipe for catastrophic storms, droughts, floods and land-gobbling sea-level rise that would hit poor countries disproportionally hard.

A major sticking point was the insistence of some developing nations like China and India, their growth fuelled by fossil fuel combustion, to be guaranteed less onerous emissions curbs compared to wealthy nations.

In hotly disputed language, some wanted the new deal to impose "commitments" on developed countries, whose long history of emissions they blame for the current state of affairs, and seek only "efforts" from emerging economies.

The West, though, insists emerging economies must do their fair share, considering that China is now the world's biggest emitter of CO2, with India in fourth place after the United States and Europe.

A draft text that negotiators mulled over on Saturday underlined that the pact would be "applicable to all parties".