OTTAWA (CP) - A prime minister who now promises to fight climate change once ridiculed the Kyoto accord as a money-sucking socialist scheme and said he would battle to defeat it.

Stephen Harper derided the global treaty and questioned the science of climate change in a 2002 fundraising letter sent to members of his now-defunct Canadian Alliance party. With polls showing the environment is a top priority with voters and Harper keen to bolster his environmental credentials, the letter could prove embarrassing.

It was circulated Tuesday by the Liberals, who said it unmasks Harper as a climate-change denier.

"Kyoto is essentially a socialist scheme to suck money out of wealth-producing nations," says the letter, signed by Harper.

"Implementing Kyoto will cripple the oil and gas industry, which is essential to the economies of Newfoundland, Nova Scotia, Saskatchewan, Alberta and British Columbia . . .

"Workers and consumers everywhere in Canada will lose. THERE ARE NO CANADIAN WINNERS UNDER THE KYOTO ACCORD."

He also blasted the treaty for targeting carbon dioxide - which he said is "essential to life" - and played down the science of climate change as "tentative and contradictory."

Harper went on to promise a "battle of Kyoto" in hope of defeating the Chretien Liberals' efforts to implement the treaty legislation in the House of Commons.

"But we can't do it alone. It will take an army of Canadians to beat Kyoto, just as it did to beat (the) Charlottetown (constitutional accord)," he wrote.

These days, Harper avoids critcizing the Kyoto accord, and simply dismisses its targets as unattainable.

Kyoto calls for a six per cent cut in greenhouse gas emissions from 1990 levels by 2012. Canada's emission levels have risen 27 per cent since 1990.

The prime minister's office would not comment on the letter but pointed out that the emission levels occurred under the previous Liberal government.

Now, with public-opinion polls indicating that climate change is becoming a dominant political concern for Canadians, the prime minister is promising serious action.

He intends to introduce a vastly revamped version of his Clean Air Act in the coming months. The original legislation has been ridiculed by opponents and opinion-makers as a work in progress that fails to set reduction targets before 2050.

The Liberals said the letter proves Harper isn't serious about tackling climate change.

"It's no wonder Mr. Harper's sudden change of heart is hard for Canadians to swallow," said Liberal MP Mark Holland.

"Now, suddenly, because he has seen the polls and realized the political opportunism of going 'green,' the prime minister has launched a new campaign - that of trying to convince Canadians that he actually cares about the environment.

"Well, no one is buying it."