British prime minister David Cameron has praised Prime Minister Julia Gillard's carbon pricing plan as bold and ambitious.

In a letter obtained by Fairfax newspapers, Mr Cameron said Ms Gillard's policy "will add momentum to those, in both the developed and developing world, who are serious about dealing with this urgent threat".

"I was delighted to hear of the ambitious package of climate change policy measures you announced on 10 July and wanted to congratulate you on taking this bold step," he wrote.

The Conservative Party leader's endorsement of Australia's plan to impose a carbon tax undercuts a campaign against the scheme by fellow conservative, Opposition Leader Tony Abbott.

Climate Change Minister Greg Combet has sought to highlight the differences in the positions of Mr Cameron and Mr Abbott.

"The UK Government certainly doesn't have any questions about the climate science like Tony Abbott has," he said.

"The UK Government respects the advice of scientists and economists unlike Tony Abbott who goes around attacking both, so it's a pretty stark contrast I think."

But Mr Abbott says the carbon pricing plan goes too far.

"[Gillard] told us that it was necessary to do to this to catch up with the rest of the world - in fact what this does is put us way out in front of the rest of the world. That's what David Cameron's letter suggests," he said on Sunday, in response to the letter.

"The British have given themselves an out clause - they will only proceed with further deep cuts if on review they find the rest of the world is similarly proceeding.

"Britain is a very different country. Britain has deindustrialised over the last generation. Britain has exported its emissions to countries that do its manufacturing for it.

"We are a resource-intensive economy. We're an economy that produces an abundance of coal and gas. What is appropriate for Britain is not necessarily appropriate for us."

Meanwhile, Fairfax reports that Mr Abbott has asked Auditor-General Ian McPhee to launch a probe into whether the Federal Government's $25 million ad campaign to sell the policy is deceptive and breaches political advertising rules.

Earlier this month Ms Gillard defended spending $12 million of taxpayer dollars on television advertising of her carbon tax, saying it is about providing facts.

The Government plans to fork out $12 million on the ads and another $13 million to print leaflets, run websites and fund other publicly available material.

The draft carbon tax legislation was released for public comment on Thursday.

Thirteen pieces of legislation that form the backbone of the carbon tax package were posted on the Government's Clean Energy Future website.

Mr Combet says submissions close on August 22.

AAP/ABC