"Listen, the United States, for national security reasons and economic security, needs to diversify away from fossil fuels. And so we've put out a strategy to do just that. I can't wait to share it with our G8 friends," he told reporters in Denmark.

Climate change is a top-of-the-agenda issue at the G8 meeting. The United States, the world's biggest polluter, is the only one of the eight industrialised countries at the summit not to have signed the Kyoto treaty to cut carbon emissions. The treaty took effect in February.

"Kyoto didn't work for the United States and it, frankly, didn't work for the world" because many developing nations were not included, Bush said. He said he was looking for solutions beyond Kyoto.

"I would call it the post-Kyoto era, where we can work together to share technologies to control greenhouse gases as best as possible," Bush told the news conference outside the Danish capital Copenhagen.

Despite speculation in the British media, US officials said on Tuesday Bush had not softened his stance on Kyoto ahead of the meeting of G8 leaders from Britain, Canada, France, Germany, Italy, Japan, Russia and the United States.

But in words viewed by other countries as conciliatory, Bush said: "I recognize that the surface of the Earth is warmer, and that an increase in greenhouse gases caused by humans is contributing to the problem."

$60 A BARREL

The United States, the world's biggest importer of oil, relies heavily on the volatile Middle East for its fuel at a time when crude prices are near record levels around $60 a barrel.

Washington has been focusing its efforts in alternative energy on biofuels that use sugar cane, vegetable oils or grain oils to produce green transport fuels ethanol and biodiesel.

"We spent about over $20 billion last year on research and development on new technologies that we are willing to share with the world. There's no doubt in my mind that we'll be driving a different kind of automobile within a reasonable period of time -- one powered by hydrogen," Bush said.

Faryar Shirzad, deputy US national security adviser for international economic affairs, told reporters enroute to Scotland that there had been an effort "to take what has been an issue where there have been differences and to use the G8 as a way to find the common ground".

As officials worked to finalise agreements, Shirzad said he was hopeful a consensus view would emerge reflecting "the robust set of initiatives that the countries of the G8 will undertake dealing with the interrelated challenges of climate change, energy security, economic development and then dealing with the problems of pollution".

The British director of leading environmental group Greenpeace said Bush's comments were nothing new and urged other G8 leaders to isolate him at this week's summit.

"We have about a decade to sort this problem out. Bush is saying he will do what he can, but there is no firm commitment," Greenpeace's Stephen Tindale told Reuters. "It is more than disappointing. It is deeply angering."

Tindale said Bush had already acknowledged in 2001 that humans were contributing to global warming and added that his comments in Denmark made clear that the US government would not intervene to curb emissions.

"The rest of the G8 countries should insist on a strong, clear message on climate change, even if the result is a split communique."