"His primary focus will be to build a stronger political foundation for international action on climate change ..," she said in a written statement to parliament.

Under Britain's presidency of the group of eight rich nations and the European Union last year, and supported by growing scientific consensus on the scale of the problem, global warming moved up the political agenda.

But while there is a broad agreement that something should be done on climate change after the Kyoto Protocol expires in 2012, there remain many big opponents.

Chief among these is the world's biggest polluter and Kyoto enemy the United States which argues that targets and timetables to cut emissions of climate-warming gases like carbon dioxide from burning fossil fuels would spell industrial Armageddon.

Fuel hungry China, which is building a coal-fired power station a week to feed its booming economy, is likewise not bound by Kyoto.

Beckett said she was creating a new "strategic priority" in a government white paper on Britain's diplomatic priorities.

"Achieving climate security by promoting a faster transition to a sustainable, low carbon global economy" is the wording of that priority.

"Climate change has become a core foreign policy challenge," she added.

Ashton, 49, a career diplomat and environmental activist with a scientific background, was posted to Beijing from 1981-84 and then headed the China desk at the foreign office for another two years.

Between 1993 and 1997, he was based in Hong Kong as deputy political adviser to Governor Chris Patten in the run-up to the handover to China of the British colony.

He has written in depth on the danger climate change poses to the political stability and security of the planet -- describing it as potentially as catastrophic as nuclear war.