COPENHAGEN — A leaked draft prepared by Denmark but reportedly compiled with assistance from the U.S. and the U.K. threatened to disrupt proceedings at the U.N. climate change conference, infuriating developing countries who feared the proposal would force them to shoulder more of the burden for reducing emissions.

The uproar began Tuesday afternoon when British newspaper The Guardian leaked portions of a draft treaty on its Web site. According to the report, the Danish presidency of the Climate Change Conference, or COP15, was going to propose 2020 as the year in which global emissions peak, although it admitted it would take longer for developing countries' emissions to reach their plateau.

The text also suggested developed nations should reduce their emissions by 80 percent by 2050 compared with 1990 levels.