China's chief climate change negotiator said on Saturday that some developed nations were trying to rewrite the Kyoto Protocol to shun their emission cut obligations, which stymied the UN climate change talks.

Su Wei, also head of the climate change department of the National Development and Reform Commission, said the underlying purpose of them doing so was to avoid setting the emission cut target after 2012, a key issue of the ongoing talks.

Some wealthy countries want a substantial amendment to the Kyoto Protocol, he told reporters on the sidelines of the UN climate change talks held in north China's Tianjin.

"That is a retreat from the past meeting. Any moves that aim to overthrow the Kyoto Protocol should be denounced," he said.

After three rounds of talks this year, about 3,100 delegates from 177 parties under the UNFCCC (United Nations Framework Convention on Climate Change) and the Kyoto Protocol gathered in Tianjin to pave the way for "concrete outcomes" at the year-end Cancun summit in Mexico.

However, as the week-long meeting is due to end Saturday, disagreement remains wide as rich and poor nations are divided over a range of issues such as whether to include all the major greenhouse gas emitters into a new treaty or to extend the Kyoto Protocol.

In response to some rich countries' accusations that China had failed to uphold its commitment made at last year's Copenhagen meeting, Su said China's support for the Copenhagen accord was "consistent" and "staunch."

"The Copenhagen accord reaffirms the principals of the Kyoto Protocol, the UNFCCC and the Bali Road Map. We have always been in support of turning agreements reached by leaders at Copenhagen into the negotiation text we are discussing currently," he said.

He also noted some rich countries were trying to create an impression that developing countries were blocking the negotiations.