The summit host, Russian President Vladimir Putin, has made "energy security" one of the main themes of the meeting, pushing environmental issues, which took centre stage at the G8 meet in Gleneagles last year, lower down the agenda.

The G8 leaders agreed to disagree on climate change, as well as the role of nuclear energy, and approved a document on the security of energy supplies on Sunday which recognised that G8 members would each deal with the issue in their own way.

"We will continue to work to reduce greenhouse gas and deal effectively with the challenge of climate change," they said in the statement.

But Chirac echoed environmentalists' views that the G8 leaders should not ignore alarm bells -- such as extreme weather conditions -- that they say are already ringing.

"Emergency signs are going up right across our planet," said Chirac. France suffered a heatwave three years ago that caused the deaths of many elderly citizens.

"Such phenomena are the first pre-cursory signs of even bigger disasters which could lead to millions of refugees fleeing hostile environmental conditions."

Green groups want the G8 leaders to unanimously back the Kyoto Protocol, an agreement on cutting emissions of the "greenhouse gases" blamed for global warming.

It has been hampered by the fact that US President George W. Bush withdrew support for the protocol in 2001.

Chirac said he regretted the fact that the United States had not approved it.

Referring to Canada, which has said it cannot meet its Kyoto obligations and might not agree to an extension of the pact, Chirac said others had to stick to their commitments.