Rural independent MP Tony Windsor has threatened to torpedo plans to put a price on carbon unless the Greens stop making ''unilateral'' statements about the details of the proposed scheme, including an insistence that petrol prices rise.

Incensed that the Greens senator Christine Milne said transport, including petrol, should be covered by the scheme, Mr Windsor said he would not accept increased transport fuel costs for country people.

The New England independent, whose vote will be critical to any legislation passing the House of Representatives, said he was prepared to walk away from the whole process if necessary.

''The Greens want to be very careful about where they are going on this or they won't see anything in the Senate,'' he told the Herald yesterday.

''If there's anything like that in the document, I won't be supporting anything in the lower house.''