DOHA, Dec 8 - Almost 200 nations extended on Saturday a weak U.N. plan for fighting global warming until 2020, averting a new setback to two decades of U.N. efforts that have failed to halt rising world greenhouse gas emissions.

The extension of the Kyoto Protocol keeps it alive as the only legally binding plan for combating global warming even though it will cover developed nations whose share of world greenhouse gas emissions is less than 15 percent.

(Reporting By Alister Doyle)