Labor has called for a factual debate on climate policy as independent analysts said the coalition's $35 billion costing of Labor's plan is "not a credible estimate".
Bloomberg New Energy Finance is cited in the government's claim, but say the coalition has cherrypicked figures to put an expensive price on Labor's international offsets policy.
Under Labor's plan companies will buy international offsets when they can't meet their emissions reduction targets.
The coalition has chosen the highest point in the 10-year forecast for European carbon credits and assumed 50 per cent of Australia's abatement for the next decade is bought at that price, Bloomberg NEF's Kobad Bhavnagri said.
He likened it to saying petrol is going to cost $10,000 this year by assuming a motorist buys it all on Boxing Day.
Government officials have confirmed they have not costed Labor's policy, as pressure continues to mount on the opposition to provide further details about the international offsets plan.
Head of the Department of Prime Minister and Cabinet Martin Parkinson wrote to Labor leader Bill Shorten confirming it's misleading to release modelling without acknowledging underlying assumptions and limitations.
"He has warned in a letter to us that people shouldn't use modelling for misleading purposes and he's cautioned against anyone thinking that his department has modelled Labor's policies," Mr Shorten told reporters in Cairns.
"What we need in Australia at the moment is less scare campaign and more facts."
Labor is proposing an emissions reduction target of 45 per cent by 2030 on 2005 levels, compared to the coalition's goal of a 26 per cent reduction.
Prime Minister Scott Morrison wants Mr Shorten to reveal the economic cost his higher targets will have.
"Tell us the price, Bill. Tell us the price," he told reporters in Melbourne.
Australian Associated Press
