(Bloomberg News) China, the U.S. and India, the three biggest polluters, maintained resistance to a time line leading to the next agreement on global warming, threatening efforts to keep alive the only limits on fossil fuel emissions.

European Union Climate Commissioner Connie Hedegaard said she hasn't yet won backing for her demand for a "road map" pointing to the next climate agreement because some nations are holding back support. She indicated that China and India remained a block. Last night, the U.S. said it won't agree to begin talks for a legally binding deal.

"The responsibility lies very, very heavily on the shoulders of those big ones that are not giving in," Hedegaard said at a news conference in Durban, South Africa. "I'm concerned about the pace. There isn't much time left. If there is no further movement from what I have seen at four o'clock in the morning, there will be no deal."

Two weeks of climate talks led by the United Nations are due to end today. Divisions are deepening between envoys from more than 190 countries about how to limit fossil-fuel emissions after restrictions in the Kyoto Protocol expire next year.

'Crunch Now'

"The crunch now is between two powerful coalitions -- the U.S., China and India pushing for nothing to be decided until after 2020, and the EU, the islands and Least Developed Countries on the other pushing for a Durban legal mandate to kick off treaty negotiations right away," said Mark Lynas, climate change adviser to Maldivian President Mohamed Nasheed. "Postponing action for another decade would fatally undermine the credibility of the entire UN process."

The talks are in a "big crisis" because of opposition by the biggest emitters, said Martin Kaiser, head of international climate politics at the environmental group Greenpeace. "It's now a big, big task to prevent a crash of the conference by the end of today."

South Africa, which is mediating the talks, called an impromptu meeting of ministers and senior negotiators tonight as talks stalled over when to begin negotiations for a new accord and whether an agreement should be legally binding.

The EU today rejected the host country's proposal for a negotiating timeline leading to a new "legal framework" after 2020. Small developing countries also oppose the language because it delays action, according to Kevin Conrad, head of Papua New Guinea's delegation in Durban.

'Vague' Language