A carbon tax proposed by the Labor-Greens alliance will dramatically force up the operating costs of heavy transport according to The Nationals Senator for New South Wales John Williams.

Senator Williams and the Nationals candidate for Northern Tablelands Charlie McCowen have met with Ted Nowlan from Nowlan Haulage of Glen Innes to discuss the likely impost on companies such as his.

Senator Williams said heavy vehicles are responsible for 2.6% of Australia's greenhouse gas emissions.

He said every $10 per tonne tax placed on carbon emissions will add 2.7 cents per litre to the cost of diesel.

"If, as the Greens want, a carbon tax of $26 a tonne is imposed, that will add 7 cents a litre to the cost of a litre of diesel.

Many transport operators are struggling under increased registration charges and regulations, and a fuel price increase that will do absolutely nothing to cool the globe will make it even tougher.

Freight is brought into northern towns by road. Transport companies would have to pass on these additional costs to survive, and the consumer will end up paying more.

Once the full details of the carbon price is known, I would suggest people contact the Member for New England Tony Windsor and let their feelings be known. As the Greens and other Independents have declared their hand on the carbon tax, it will be Mr. Windsor who has the deciding vote on whether Australia gets a carbon tax", Senator Williams said.