"One year on from the UK Gleneagles Summit, where the G8 committed to taking action on climate change, this crucial issue must not be allowed to fall by the wayside," said Martin Rees, president of the UK's Royal Society.

Rees is a signatory to the statement from the science academies of the G8 and China, Brazil, India and South Africa.

"The G8 must demonstrate that this was a serious pledge by integrating climate concerns with their discussions regarding security of supply," he said.

Britain pushed global warming to the top of the agenda during its presidency of the G8 in 2005, eliciting promises of action from some of the world's major polluters.

But energy supply worries have increased as Russia briefly turned off gas supplies in December in a dispute with Ukraine, Iraq's insurgency has escalated as has a nuclear row with Iran, factors that boosted oil prices to record levels.

Environmentalists say the topic has dominated discussions in the lead up to the G8 summit in St Petersberg from July 15-17, pushing a follow-up to the resounding Gleneagles climate change declarations all but off the agenda.

US President George W. Bush, who signed the Gleneagles declaration but has not ratified the Kyoto Protocol on tackling human-caused global warming by cutting carbon dioxide emissions, has called for reduced US dependence on imported oil.

Partly as a result of energy security worries there has been a surge in interest in nuclear power and coal as power sources.

"As some of the most intensive users of energy in the world, the G8 nations bear a special responsibility to help stimulate the clean energy revolution that will deliver economically, environmentally and socially while ensuring the lights stay on," Rees said.