A leaked Danish draft document for the Copenhagen climate change conference has caused an uproar in the developing world for demanding less from developed nations and setting sensitive limits.

Lumumba Di-Aping, the Sudanese chairman of Group of 77 and China, a group of developing countries, said the Danish text was unacceptable. The text was not in line with the common but differentiated responsibilities under the United Nations Framework Convention on Climate Change, he said at a press conference Wednesday.

Commenting on a proposed "peak" of global emissions in the draft, China's chief negotiator Su Wei said Tuesday that setting a peak year for emissions was unfair to nations in the developing world and "it is still early to talk about a peak year."

Noting that emissions in the United States and Japan were still rising, Su said developed nations should reach the peak of their emissions first.

The U.N. convention recognizes the need of developing nations for increasing emissions, he said.

In an effort to iron out the rift between developed and developing nations, the top U.N. climate official, Yvo de Boer, said Wednesday that the text has not been on the table "in a formal sense" and was only the basis for discussions among some countries.

"I think a number of countries are nervous about the text because they see it as being unbalanced," he said.