But talks in the Thai capital were expected to drag on late into the night, with China and Europe facing off over the costs and levels of greenhouse gas emissions.

"Some countries are being difficult and we don't know how difficult until we come to the final moment," said one delegate who declined to be named.

China, the world's number two emitter of greenhouse gases after the United States, wants the IPCC report to exclude wording about scenarios for stabilising gas levels near current levels.

Beijing objects to any language that suggests a cap on emissions or stabilisation levels, wording it feels could leave China vulnerable to demands in future climate talks to slow rapid economic growth or spend vast sums on cleaner technology.

Scientists and government officials from more than 100 countries have been meeting since Monday to discuss the report by the IPCC, which draws on the work of 2,500 scientists.

The report is the third to be released this year by the UN climate panel. The previous two painted a grim future of human-induced global warming causing more hunger, droughts, heatwaves and rising seas.

A draft of the latest report estimates that stabilising greenhouse gas emissions will cost between 0.2 percent and 3.0 percent of world gross domestic product by 2030, depending on the stiffness of curbs imposed on rising emissions.

EU-CHINA RIFT

For example, by 2030, the costs of letting greenhouse gas concentrations rise to 650 ppmv (parts per million volume) of carbon dioxide-equivalent are 0.2 percent of global gross domestic product, it says.

The lowest level of 445 ppmv would be the most costly and arguably impossible to achieve. Current concentrations are now at about 430 ppmv of CO2-equivalent and rising sharply.

The first delegate said no particular stabilisation target had been set in the talks. But the European Union says a 2 degree Celsius rise is a threshold for "dangerous" changes to the climate system, implying a fairly minimal rise in greenhouse gas concentrations.

"The EU wants a long way below 550 ppm. China is somehow wanting to exclude information about the low scenarios and others are too," the delegate said.

Michael Muller, a junior minister in Germany's environment ministry, took a swipe at China for its perceived intransigence.

"The delegation from China tries massively to prevent such a position and there are not a few states that hide behind them," he said told reporters in Bangkok.

Global environment group WWF said on Thursday China should not be labelled a villain and Chinese delegates had been raising useful issues during the meeting.