Reports yesterday suggested the government is settling on $20 per tonne of carbon emitted as its preferred position on the starting price for its proposed carbon tax when it starts in July next year.

In a speech to the National Press Club on Wednesday, the Climate Change Minister, Greg Combet, also hinted the $20 price is in the frame when he used the figure while referring to the impact on heavy industry.

But according to the Herald the Greens, whose support Labor needs to establish the tax, are advocating a carbon price well above $20. The Greens senator Christine Milne said yesterday: "There has been no decision in the Multi-Party Climate Committee about the starting level for the pollution price."

The Herald also understands cabinet is yet to approve a government position on a starting carbon price.