China will not make a binding commitment to reduce carbon emissions, putting in jeopardy the prospects for a global pact on climate change.

Officials from Beijing told a UN conference in Bonn yesterday that China would increase its emissions to develop its economy rather than sign up to mandatory cuts.

The refusal is a setback for President Obama’s efforts to drum up support for an agreement at Copenhagen in December on a successor treaty to the Kyoto Protocol. As argument erupted between rich and poor nations at the Bonn talks, Yvo de Boer, the UN climate change chief, said that a worldwide pact to prevent global warming was “physically impossible”.

Hopes that Copenhagen might deliver tougher carbon reduction targets were dashed further when Japan failed to make a significant commitment to reduce emissions. Taro Aso, the Japanese Prime Minister, said on Wednesday that Japan would cut greenhouse gas emissions by 15 per cent by 2020 from levels in 2005. The Japanese commitment is a mere 2 per cent improvement on its commitment under Kyoto.

Responding to the Japanese proposal, the UN chief made no attempt to hide his disappointment. “For the first time in my two and a half years in this job, I don’t know what to say,” he said. “We’re still a long way from the ambitious emission reduction scenarios that are a beacon for the world.” The Chinese rejection of cuts emerged after talks in Beijing between Todd Stern, the US climate change envoy, and the Chinese Government, in which Mr Stern appears to have backed down from earlier calls that China make a commitment to reduce CO2 emissions.

Qin Gang, a Chinese Foreign Ministry spokesman, said that China was still a developing country and its priority was to develop its economy, alleviate poverty and raise living standards. “Given that, it is natural for China to have some increase in emissions, so it is not possible for China to accept a binding or compulsory target,” he said.

The climate negotiations have been dogged by debate over which nations should take primary responsibility for cutting carbon emissions from the fuels such as coal and oil.

The Bush Administration had insisted that it would not agree to mandatory cuts as long as developing nations increased emissions. The Obama Administration has taken a softer line, accepting that China and India could not be expected to make equal commitments to developed economies. However, Mr Stern recently said: “They do need to take significant national actions that they commit to internationally, that they quantify and that are ambitious.”

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