COPENHAGEN: U.N. climate talks were thrown into disarray Monday as developing countries blocked negotiations, demanding that rich countries raise their pledges for reducing greenhouse gas emissions.

Representatives from developing countries said they refused to participate in any working groups at the 192-nation summit until the issue was resolved.

The move was a setback for the Copenhagen talks, which were already faltering over long-running disputes between rich and poor nations over emissions cuts and financing for developing countries to deal withclimate change.