BEIJING: Rich nations should cut their greenhouse gas emissions by at least 40% by 2020 from 1990 levels as part of a new global climate change pact, China said on Thursday, spelling out an ambitious stance ahead of negotiations.

Developed countries should also give 0.5 to 1.0 percent of their annual economic worth to help other nations cope with global warming and curtail greenhouse gas emissions, China said in the document, laying down demands for a conference in Copenhagen in December meant to seal a new climate change pact.

The pact must ensure wealthy nations "take on quantified targets to drastically reduce emissions", said the statement, issued by the National Development and Reform Commission (www.ndrc.gov.cn), which steers Chinese climate change policy.

The Copenhagen conference is looking to agree on a treaty that will build on the current Kyoto Protocol.

The Chinese document also pointedly demands that a new treaty "ensure developed countries that have not ratified the Kyoto Protocol assume corresponding and comparable emissions reduction commitments".

The United States under President George W. Bush set aside the Kyoto Protocol, citing among its reasons that China and other big developing countries did not assume emissions caps.

Beijing's latest statement also says that it and other developing countries must be allowed to balance efforts to combat climate change with the need to develop.

"Developing countries must undertake appropriate mitigation actions within a framework of sustainable development," it says.

To achieve that goal, rich countries must consider contributing 0.5 to 1.0% of their gross domestic product every year to a fund to help poorer countries adapt to global warming and buy green technology, China says.