Federal Treasury analysis shows the Opposition's direct action climate change policy would cost twice as much as a carbon tax for the same reduction in emissions.

The analysis has been released following a Freedom of Information (FOI) request.

Both major parties have committed to reducing carbon emissions by 5 per cent by 2020.

The Treasury analysis says the Coalition's direct action plan would be more expensive because it forgoes opportunities for cheaper, international sources of abatement and would be generally less effective.

The modelling says a carbon price of $62 a tonne in 2010 dollars would be the cost needed to abate 159 million tonnes in 2020 from the direct action plan.

The cost would be $29 a tonne if international market-based permits were used.

Real gross national income would be cut by 1 per cent in 2020 under a direct action plan compared with a reduction of 0.5 per cent using a market-based mechanism, Treasury said.

The Government wants a carbon tax on big polluters up and running by mid-2012 with a starting price of $23 a tonne.

It will then transition into an emissions trading scheme with a floating price three years later, in mid-2015.

The Coalition has stated its direct action plan, funded entirely from the federal budget, would cost $10.5 billion in its life until 2020.

But after the release of the modelling on Friday, Treasurer Wayne Swan said the Coalition's scheme would cost the budget at least $48 billion in the period.

"This would mean that the average Australian household will have to pay an extra $1,300 in taxes," he said.

Mr Swan says Treasury's advice of putting a price on carbon pollution is the cheapest and most efficient method to cut carbon emissions.

"It is consistent with the advice we've seen from leading economic institutions like the IMF, OECD, Productivity Commission, and the overwhelming majority of respected economists across the nation," he said.

However, Opposition climate change spokesman Greg Hunt has dismissed the figures.

Mr Hunt said the modelling was "dodgy" because it was based on a fixed price rather than a capped policy, which would be fully funded by savings made by the Coalition.

"That's why when we model things, we model them on the price we said it would be," he said.

"This is the fourth time that the Government has released it (the figures) and, more than that, it was wrong the first time and it's wrong now

"It's wrong because Treasury hasn't been allowed to model a fixed-cost policy."

Labor pains

Prime Minister Julia Gillard insists she is the right person to lead the Government. ( AAP: Lukas Coch )

The release of the analysis comes as a rare break to the onslaught of speculation over the Labor Party leadership.

On Friday Prime Minister Julia Gillard dismissed speculation of a leadership plot against her in the wake of the High Court ruling on the Malaysia refugee swap deal.

The High Court struck down the Government's plan to send asylum seekers to Malaysia in return for taking refugees, with Ms Gillard then blaming the court for a "missed opportunity" and accusing Chief Justice Robert French of inconsistency.

Ms Gillard's attack on the High Court prompted Attorney-General Robert McClelland to restate the Government's respect for the High Court.

Some unnamed Labor sources are reportedly suggesting Ms Gillard has lost authority and that her political future is bleak, with several polls showing the Government has taken a sharp battering over the carbon tax and its immigration policies.

Ms Gillard says she is the best person for the top job and she insists no-one in caucus has raised the leadership issue with her.

"I'm not going anywhere. I'm the best person to do this job. And I'll continue to do it. And what this job is about is leading the nation to a better future," she said.

Speculation in newspapers on Thursday suggested former Queensland premier Peter Beattie had been approached to run for a federal seat, with a view to rescuing federal Labor from its dire poll position.

On Friday Mr Beattie ruled out running for Prime Minister's job, saying Julia Gillard was the best person to lead the country.

Mr Beattie says changing leaders at this point would destroy the Government.

"I just say to all my colleagues in the party at a state and federal level: Hold your nerve. This is a time to hold your nerve and not to change the leader," he said.

ABC/AAP