Michael Meacher, a former environment minister who last week launched a campaign to move the Labour Party in a new direction, told GMTV television that action on climate change could provide the "new vision" the party needed.

"This is the one overriding overall political issue which challenges the future of the human species on this planet," said Meacher, who has refused to rule out a challenge for the Labour leadership.

"We are very good in this country at getting behind a collective cause which we all know has to be absolutely hugely overridingly important, as we did in 1939," Meacher said.

"I think we are at war over climate change and I think we can lead the country."

He declined to rule out a challenge to finance Gordon Brown, the favorite to succeed Prime Minister Tony Blair when he steps down by September, saying the issue was "for tomorrow not for today."

The priority was to outline a clear policy program as Labour faces a resurgent opposition Conservative party.

"The most important thing is that we have a new vision, a set of principles which can actually fire the imagination and galvanise our party again and I am convinced that that is combating climate change," he added.

He said the government's refusal to include such regular scrutiny in new climate change legislation was "a mistake".

A Climate Change Bill will be unveiled in next week's Queen's Speech, which announces the new legislative season, but is not expected to contain the firm yearly targets demanded by environmental campaigners.

Meacher said the bill should set a three percent annual reduction target for businesses and individuals and ensure the government was forced to report progress each year.