"The United States takes this issue seriously,"  Mr Bush said.

"The new initiative I'm outlining today will contribute to the important dialogue that will take place in Germany next week."

He promised that America would work with other countries "to establish a new framework for greenhouse gas emissions for when the Kyoto Protocol expires in 2012".

The President's language is a marked contrast to that of earlier in his administration when he questioned whether climate change was a man-made problem and refused to ratify the 1997 Kyoto Protocol, not least because it exempted China and India – who were emerging as competitors – from the first round of emissions cuts.

But his administration also made plain today that it remained opposed to Germany's call for the imposition of a strict upper limit, allowing global temperatures to increase by no more than 2C.

These would mean a worldwide reduction in emissions effectively of 50 per cent below 1990 levels by 2050.

Nor is Mr Bush willing to accept EU proposals for a global carbon-trading program under which companies would buy and sell pollution permits.

Paula Dobriansky, the US Under Secretary of State, told reporters today  that the administration doubted the effectiveness of measures that "would restrict economic growth and investment for new research".

She added: "There is not a one-size-fits-all or silver-bullet solution to climate change."

The US argues that its own progress in cutting carbon dioxide emissions in 2005 shows that a less rigid policy of promoting new technology can also achieve results.

Mr Bush said that all countries, including "rapidly growing economies like India and China" needed to "establish midterm management targets and programmes that reflect their own mix of energy sources and future energy needs".

His proposals did little to impress environmental groups.

Brent Blackwelder, president of Friends of the Earth, branded them a "a complete charade", adding: "It is an attempt to make the Bush administration look like it takes global warming seriously without actually doing anything to curb emissions."

There was a more muted reaction from European leaders such as British Prime Minister Tony Blair and Angela Merkel, the German Chancellor, who have led international pressure for more action on climate change.

Mr Blair, speaking in South Africa, said there was now a "real chance" of a deal on global warming at the G8 summit and then appealed for greater understanding over Mr Bush's position.

Mr Bush has also sought to dampen down growing tensions with Russian President Vladimir Putin, over the stationing of US interceptor missiles in Eastern Europe, inviting him to a meeting at the Bush's family holiday residence at Kennebunkport, Maine, next month.

Today, however, Mr Putin raised the rhetorical stakes further, saying that the recent test of a new Russian missile was a direct response to US actions and "imperialism" in world affairs.

"We are not the initiators of this new round of the arms race," he added.