CHINA'S Chief Climate Negotiator Su Wei has reaffirmed the nation's commitment to lower emissions relative to economic output while dismissing reports that it will adopt an absolute cap on greenhouse gases.

The Financial Times and Independent newspapers both said last month that China is looking to introduce a cap in 2016. The Independent cited a proposal by the National Development and Reform Commission, the economic planning agency where Su works. The FT cited Jiang Kejun, an NDRC carbon-policy researcher.

"The paper quoted an expert," Su said yesterday in an interview in Bonn, where two weeks of climate talks began on Monday. "It's not necessarily presenting the view of the government or the NDRC. The NDRC would reaffirm that we have committed to a carbon-intensity target by 2020."

Su's comments are the first by a senior Chinese negotiator since the reports were published. While not an outright denial, they suggest China isn't ready to announce a cap at the United Nations talks in Germany, where such a move may have spurred other nations to step up measures against global warming.

"What I have seen so far is speculation in the press, but I haven't seen China really coming out and saying it," Artur Runge-Metzger, the European Commission's lead envoy at the talks, said in an interview. "It could really unlock the negotiations and show leadership by China. It could be changing the game, depending on the content."

Envoys at the UN talks aim to craft a new climate treaty by 2015 that will take effect in 2020. They're also discussing how to raise emission-reduction targets in the meantime, with the World Bank warning that global temperatures may increase by 4 degrees Celsius, double the internationally agreed goal.

The average concentration of carbon dioxide in the atmosphere exceeded 400 parts per million last month for the first time at the Hawaiian monitoring station that first began tracking the gas in 1958. That threshold hasn't been passed in millions of years, studies show.

"Allowing the concentration to rise further would be suicidal," Nepalese envoy Prakash Mathema said yesterday in Bonn. "We are behind schedule and time is not on our side."

The emphasis at previous UN talks has been for developed nations to take the lead by adopting absolute emission caps, with developing countries taking voluntary measures.