The flyover at Dunbeath north of Berriedale

MSP Jamie Stone said the NDA, which is overseeing the clean-up at Dounreay, was in favour of the plan for the steep and twisting Berriedale Braes.

The NDA said it was looking at a wide range of projects to soften the blow of the site's eventual closure.

Transport Minister Tavish Scott is to visit the Braes later this summer.

Mr Stone described the Berriedale Braes, which can become congested as drivers slow to negotiate a steep drop and climb, as a "tourniquet" on a vital supply route to the north.

He is pushing for a flyover to be constructed similar to one a few miles further along the road at Dunbeath.

'Very expensive'

The MSP is trying to find funding for the project and contacted the NDA, which is overseeing the 30-year �2.9bn decommissioning of Dounreay nuclear plant.

He said: "It is significant that NDA said in their letter to me that they would consider supporting this project. It is going to be very, very expensive.

"A lot of money has been spent on the A9, but this very, very dangerous hairpin bend in effect is a tourniquet on a vital supply route into Caithness from the south and into Orkney and Shetland."

Transport Minister Tavish Scott has told Mr Stone that he will visit the site during the summer.

The NDA is trying to reduce the impact of the Dounreay clean up

John Farquhar, NDA director for region four, which covers Caithness, said the authority supported the flyover "in principle".

The public body was set up 14 months ago through an act of parliament.

Mr Farquhar said: "Part of that act placed a responsibility on us to pay very close attention to the socio-economic welfare of the communities around the sites for which we are responsible.

"For example, at Dounreay, the decommissioning will result in the loss of 3,000 jobs and so what we are keen to do is soften the impact of that on the local community."

He said the NDA was working with Caithness and Sutherland Enterprise, Highland Council and Scottish Executive on the best way to do that.

Mr Farquhar added: "Whilst we are in principle supportive of infrastructure projects, of which the Berriedale flyover is one, we do scrutinise them very, very carefully to make sure we are spending money in the right way."