Actress Cate Blanchett and former conservative Prime Minister Malcolm Fraser are among prominent Australians who threw their support Monday behind the unpopular government plan to tax major polluters for the carbon gas they emit.

Blanchett and Fraser were among 140 personalities and organizations who signed a petition distributed to federal lawmakers supporting the center-left government's plan to make polluters pay for every ton of carbon gas they produce in a bid to reduce the nation's greenhouse gas emissions.

The petition — whose signatories also include a Roman Catholic bishop and a Nobel Laureate scientist — is part of a $1 million national newspaper and television advertising campaign funded by environmental groups and unionists.

The conservative opposition Liberal Party is opposed to making polluters pay. The governing Labor Party wants to tax polluters starting in July 2012, and is locked in negotiations with the minor Greens party and independent lawmakers on how much the tax should be on a ton of carbon.

Opinion polls show that both the tax and Labor are unpopular with voters.

John Hewson, an economist and a former Liberal Party leader who signed the petition, said Australian business leaders were not signatories because they are historically slow to respond to economic challenges.

"The business community's starting to come on board," Hewson told reporters at Parliament House.

"It's a pity they're not leading this debate. Unfortunately, as on many occasions in the past, they come, but they come late," he said.

The Business Council of Australia, a leading business lobby, has called for the tax to be set at 10 Australian dollars ($10.69) per metric ton (1.1 tons), while the Greens want the tax to be four times higher. The government has said it will set the price by July.

Liberal Leader Tony Abbott called the proposal a "toxic tax" that businesses increasingly oppose.

Prime Minister Julia Gillard has said her government would meet its target of slashing Australia's greenhouse gas emissions to at least 5 percent below 2000 levels by the year 2020.

Australia is one of the world's worst greenhouse gas emitters per capita because of its heavy reliance on abundant reserves of cheap coal for power generation.