LONGANNET power station is to be converted to burn gas as a temporary measure to secure electricity supply.

The coal-burning plant in Fife, on the banks of the Forth, was closed last week after a coal-bearing conveyor belt collapsed.

That could take up to two months to repair and, to ensure continuity of supply, the turbines are being switched to gas as early as this week.

The move will require a consent order to be passed in the Scottish parliament early this week, giving only temporary permission for the coal-burning permission on the site to be extended.

A Scottish Executive spokesman talked down reports of imminent power cuts, saying Scotland usually exports energy south through the National Grid, and that any shortfall in Scotland will be made up while Longannet is out of action.

"This is not a panic measure, and nor is it emergency legislation," he said. "It's seen as necessary to maximise the power generating capabilities."

He conceded the generating capacity is now "tighter than normal", while Hunterston nuclear plant in Ayrshire is also closed for repairs.

This demonstration of the vulnerability of energy supply, in an old power station having its life extended with new equipment, has been seized on by supporters of both nuclear and renewable power to make the case for major new programmes for new capacity.

Tony Blair, attending the World Economic Forum in Davos, confirmed the forthcoming white paper on energy, scheduled for March, will include "the re-launch of nuclear power".