DURBAN (Reuters) - Ministers fought to save U.N. climate talks from collapse on Saturday, searching to narrow differences between rich and poor nations over how quickly to fight global warming. Ministerial negotiations in the South African port city of Durban dragged into Saturday afternoon but with many delegates due to head home, there was a strong chance real decisions would be put off until next year. That would be a major setback for host South Africa and raise the prospect that the Kyoto Protocol, the only global pact that enforces carbon cuts, could expire at the end of next year.