Such a target "would be a recipe for a Garrett recession. That is not a recession which Australia has to have," Howard told his Liberal party on Sunday.

Labor's stated policy is for a 60 percent cut in emissions by 2050 and it has made no mention of earlier targets.

"The prime minister is now looking at this issue through the prism of politics and it is blatant scaremongering...," Garrett told reporters on Monday. "Labor's policy of having a 60 percent cut in emissions by 2050 is fully backed by science."

Britain has already committed to 60 percent cuts in carbon emissions by 2050 and Canada and the European Union have set 20 percent cuts in greenhouse gases by 2020.

Labor leader Kevin Rudd said Howard's refusal to set emission reduction targets and act against climate change now posed a huge risk to Australia's future economy and environment.

"Basically we have someone who is still a climate change sceptic pretending to be part of a climate change solution and evidence of that pretence is the absence of clear-cut carbon targets," Rudd told reporters.

Australia's major newspapers on Monday charged Howard with trying to scare voters as he seeks a fifth term in office at an election expected in late 2007.

"John Howard has launched the government's climate change fright line for the federal election," wrote political editor Peter Hartcher in The Sydney Morning Herald.

"SCARE CAMPAIGN"

The Australian newspaper said Howard was linking climate change to the economy, his political strength after 11 years of economic growth, to "run a scare campaign".

Several Australian reports on reducing greenhouse gas emissions have found minimal adverse economic impact.

A 60 percent cut in emissions by 2050 would restrict economic growth by an average annual 0.1 percent of gross domestic product, said a 2006 report by the government's top scientific body and the Allen Consulting Group.

It said the Australian economy would grow by 2.1 percent in 2050 with such cuts, compared with 2.2 percent without.

Another study by the Commonwealth Scientific and Industrial Research Organisation and Monash University found a worst case scenario would see only a small dip in economic growth.

"Instead of the economy growing at 3.0 percent without a target it would be growing roughly 2.75 percent," said Monash economist Phillip Adams.

Howard, who has spent much of the past 11 years in power playing down the risks of global warming, said on Sunday that dealing with climate change would be the most momentous economic decision Australia would take in the next decade.

He said his government would implement a carbon trading scheme by 2012, but will not disclose targets for reducing emissions until 2008, after the next election.

Carbon trading involves putting a price and limits on pollution, allowing companies that clean up their operations to sell any savings below their allocated level to other companies.

Australia accounts for 1.5 percent of global carbon emissions, but relies on coal for about 80 percent of electricity, and is the world's biggest coal exporter.

While Howard's commitment to a carbon trading scheme has been welcomed, the lack of any greenhouse gas reduction targets has been criticised by green groups and climate experts.