In defence to recent accusations her government was based on a lie, Prime Minister Julia Gillard explained it is not her fault that she may introduce a carbon tax.

Five days before the August 21 poll, Ms Gillard ruled out using a tax to help reduce greenhouse gas emissions.

She, however, reversed her view, saying that because Labor now shared the balance of power in the lower house with the Australian Greens and independents, the circumstances around her original promise had changed.

"We can't just go to the House of Representatives and say, 'Here is the government's position' and five minutes later it's passed by the house," she told Network Ten on Sunday.

Ms Gillard, who vowed to set up a committee made up of MPs from all sides of politics to examine ways of pricing carbon, said the coalition is welcome to participate in the talks, although committee membership is only extended to those who agree a carbon tax in necessary.

But Opposition Leader Tony Abbott has said he would never put a price on carbon unless it became part of an enforceable international system.

The committee, to be chaired by Ms Gillard, will include Deputy Prime Minister Wayne Swan and Climate Change Minister Greg Combet (deputy chair) as government representatives.

It will hold its first meeting in October.