Energy minister John Battle tells BBC Radio 4's World at One the reasons behind the decision

Energy Minister John Battle said that the plan was based solely on economic factors, following his revelation that the UK Atomic Energy Authority (UKAEA) had advised him there is "no economic case" for supporting the reprocessing work over the longer term.

He told Radio 4's World at One: "It had absolutely nothing to do with reports earlier this week."

These had suggested that uranium may have been lost at the plant and followed other criticisms over safety. Mr Battle said: "These considerations have been going on for some time."

Earlier he outlined plans to run down the plant. He said: "Reprocessing at Dounreay will come to an end when the plant has completed reprocessing its own fuel, the Georgian highly-enriched uranium and its existing commercial contracts."

Mr Battle said they hoped to complete the commercial reprocessing work by the year 2006.

Dounreay opened on the Caithness coast of Scotland in 1957 and was seen as being at the cutting edge of Britain's nuclear technology.

Alex Salmond has welcomed the move

For 30 years it produced electricity but it has now been decommissioned. Its prototype fast reactor was closed in 1994 but some reprocessing work does go on - including reprocessing reactors from its own reactors.

Existing waste, which includes a consignment from the former Soviet republic of Georgia, will be dealt with - but not until the plant is given the all-clear by safety inspectors.

From then, the focus will be on winding-down the plant. All efforts will be channelled towards clearing up the nuclear waste in the plant's underground shaft.

BBC Correspondent Kenny McIntyre on how the decommissioning will begin

Those hoping to see a swift end to the plant will be disappointed as experts predict decommissioning will take a generation.

SNP leader Mr Salmond told BBC Radio 4's Today programme the government had made an "astonishing turn around" in its attitude to the plant, but nonetheless had made the right decision.

He added: "Anyone with an interest in these matters has known for some considerable time that Dounreay is not in a condition where it is safe to take any extra nuclear material to it.

"The only sensible thing to do is to stop that process happening."

He predicted that decommissioning would take anything up to 60 years, so there was no immediate threat to jobs in the area.

Dr Ray Nelson, director of Dounreay, tells Radio 4's World at One about Dounreay's non-commercial activities

The plant employs about 1,400 staff and the only other main industries in the area are farming and tourism.

But Mr Salmond said the government had a responsibility in the long-term to establish the area as a "centre of excellence" in high technologies, possibly in alternative energies.

Dounreay was once at the cutting edge of nuclear technology

Mr Salmond said there had been a succession of "quite astonishing and potentially dangerous" incidents at the plant, even discounting the decision to bring Georgian waste to the plant for reprocessing.

He pointed to the resignation of the head of security over concerns about policing the plant, the recent incident in which the electricity supply to the plant was inadvertently cut, as well as the recent reports that uranium might have been lost at the plant.