"Whether or not we can set a limit on a two-degree (3.6 Fahrenheit) rise in temperature I'm afraid still lacks a lot of scientific evidence and dependable and feasible research," China's top economic planner Ma Kai told journalists.

"There is especially no research that details the economic impact of a two-degree restriction, nor what kind of influence such a target would bring on the development of each nation."

Ma appeared to ignore a May report from the UN's top panel of climate scientists that said annual global economic growth would fall by only 0.12 percentage points if warming was limited to between 2.0-2.4 degrees Celsius.

The UN's International Panel on Climate Change, made up of experts from over 120 nations including China, said nations had the money and the technology to keep global warming to two degrees.

The panel said in an earlier report that increases beyond that threshold could unleash catastrophic consequences ranging from an increase in violent storms to severe drought to rising sea levels.

Ma's comments were specifically aimed at a European Union proposal calling for a limit on global warming this century to two degrees, and cutting global greenhouse gas emissions to 50 percent below 1990 levels by 2050.

The European bloc hopes to enshrine the proposal in a summit statement of the Group of Eight meeting in Germany this week.

"Concerning the EU's proposal to set a two-degree Celsius limit on global warming, I think this is a postive gesture that again shows the EU commitment to make efforts to face climate change," Ma said.

"(But) I think that the experts need to continue to earnestly research this and come up with more proofs."

China is the biggest greenhouse gas emitter after the United States.