China is thought to be the highest emitter of CO2

Climate research body the Tyndall Centre, using 2004 data, estimates the emissions are double those of Britain for the same period.

It wants rich nations to take the lead in cutting the pollution they cause.

In the last year, UK imports from China rose by 10%, nearing 6.5 million tonnes, according to a recent study.

'Rethink needed'

The Tyndall Centre report concludes that in 2004 - the most recent year in which comprehensive data is available - net exports from China accounted for 23% of its total CO2 emissions.

The authors said the emission levels are due to China's trade surplus, but are also due to the relatively high level of carbon intensity within the Chinese economy.

The report said: "The extent of 'exported carbon' from China should lead to some rethinking by government negotiators as they work towards a new climate change agreement.

"It suggests that a focus on emissions within national borders may miss the point. Whilst the nation state is at the heart of most international negotiations and treaties, global trade means that a country's carbon footprint is international.

"Should countries be concerned with emissions within their borders (as is currently the case), or should they also be responsible for emissions due to the production of goods and services they consume?"

China is believed to be the world's largest emitter of carbon dioxide.