Documents leaked to a whistle-blower project and published last week in New York Times showed that Mr Cooney repeatedly deleted warnings in official policy papers about climate change. He also emphasised doubts about the scientific research into greenhouse gases.

The revelation came just 24 hours after President George W. Bush said his administration viewed climate change as a "serious long-term" problem. The White House denied it was politicising science and said Mr. Cooney's changes were part of the normal policy review process.