THE Nationals' pre-election pledge to deliver piped natural gas to country Victoria appears doomed.

Yet another bid to extend the gas network into the bush has shown it to be simply too costly.

The $1 million Murray River Communities Gas Feasibility Study revealed the cheapest option to connect some of the promised towns, extending the pipeline from Bendigo through to Swan Hill, would still cost $67 million.

Even under that unlikely plan, residents would end up paying the highest tariffs in the state.

The new cheapest route runs from Bendigo East to Swan Hill and includes Gunbower, Leitchville, Cohuna, Kerang, Tresco, Lake Boga and Murray Downs.

The study, commissioned earlier last year as part of a pre-election pledge, was released last week.

Deputy Premier Peter Ryan said the state could not afford to go it alone and both Federal Government and the private sector would have to help pay for it.

The Government's other pledge to deliver gas to a dozen "priority" towns has stalled even though $100 million has been set aside for Avoca, Bannockburn, Heathcote, Invermay, Koo Wee Rup, Lakes Entrance, Maldon, Marong, Orbost, Terang, Wandong-Heathcote Junction, Warburton and Winchelsea.