Gore told a standing-room audience in the Danish capital that a summit in Mexico City previously scheduled near the end of next year was too late and too close to mid-term US elections.

"I do not believe that we can wait until next November or next December," said Gore, a Nobel peace prize winner for his work on raising awareness of climate change.

He called for activists to "join with me proposing that the next meeting of ministers and heads of state take place in July in Mexico City."

"I have reason to believe that the Mexican government is willing to consider undertaking the enormous amount of work that would be involved to move the date of the next meeting to the middle of the summer," he said.

Gore urged delegates to be as ambitious as possible in the Copenhagen conference that is scheduled to close on Friday but said it was virtually impossible to seal a binding treaty by then.

Developed and developing nations remain at loggerheads on key points, while the US Senate has yet to complete legislation for the world's largest economy to impose nationwide curbs on carbon emissions blamed for global warming.

But Gore, himself a former senator and ally of President Barack Obama, said he expected the legislation to pass -- and called for a deadline.

"I will ask my fellow US citizens who share my sense of urgency to join me in asking President Obama and the leadership of the US Senate to set a deadline of April 22, 2010 -- the 40th anniversary of Earth Day -- for final action on the US legislation," Gore said.

Gore said that only "reckless fools" reject the science behind global warming.

"We cannot allow Copenhagen to become Doha," Gore said, referring to long-stalled negotiations on a global free trade pact.

Future generations "will not care very much about some of the disputes that are raging here in this conference," he said.

"They will find it difficult to understand how some of these disputes could be allowed to interfere with the result that is essential for the survival of our civilization."

All rights reserved. copyright 2018 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.