The text released by the UN climate conference's host, Azerbaijan, provided two competing options that showed rich and developing nations remain far apart on how to get the funds for vulnerable countries.

"The current text contains a lot of elements that are not satisfactory and acceptable to China," Xia Yingxian, a Chinese official, told delegates at the UN negotiations in Azerbaijan.

"Yet we call on all parties to meet one another halfway," he said.

Rich nations have insisted that the donor base should be broadened to include countries that were classified as developing in 1992 but have now grown wealthy, such as China or Saudi Arabia.

China -- the world's largest greenhouse gas emitter -- has steadfastly rejected changing its status but has highlighted its bilateral aid to developing countries.

Xia said "voluntary support" is "different in nature from the obligation of developed countries to provide financial resources."