Assembly ministers are looking at the possibility of extending the life of the Wylfa nuclear power station on Anglesey, it has emerged.
The plant is due to close in four years
Economic Development Minister Andrew Davies confirmed he has asked the UK Government to look at keeping Wylfa open beyond 2010.
First Minister Rhodri Morgan told AMs the administration was still against any new nuclear stations for Wales.
Anti-nuclear campaigners expressed disappointment over the move.
The last nuclear power plant to be built in Wales, the Magnox plant at Wylfa, on Anglesey, opened in 1971 and produces around 10% of Wales energy needs. It is due to cease production in 2010.
Mr Davies said any move to extend Wylfa's life did not go against the assembly's anti-nuclear policy which is against new facilities in Wales.
But he said he has been in contact with officials in the DTI in the last few weeks to ask them to look more closely at the option of extending the station's life.
Both the plant in Preston, where Wylfa gets its fuel, is closing and so is Sellafield where its waste is processed.
But as well as being a major employer itself on the island, the power station also supplies another company Anglesey Aluminium and there are concerns more jobs would be under threat if Wylfa shuts.
Mr Davies said he wanted to make sure all options were kept open.
When challenged at first minister's questions, Rhodri Morgan said "We made it clear that ... we didn't see the need in Wales for nuclear capacity. But we have always said that Wylfa may be an exception to that for very specific localised reasons."
Plaid Cymru assembly leader and Anglesey AM, Ieuan Wyn Jones, told reporters he too supports an extension to Wylfa's life but he stopped short of backing the building of a new nuclear power station.
Conservatives spokesman Alun Cairns accused Mr Davies of "breathtaking inconsistency" and said Anglesey Aluminium and business in general need "certainty of policy and certainty of supply."
Dylan Morgan of the anti-nuclear group PAWB (People Against Wylfa B) said he was disappointed by the assembly government's move.
He said that any attempt to extend the life of the plant would increase the possibility of another station being built at Wylfa, and he claimed that such a move at an ageing nuclear plant would increase safety concerns.
Mr Morgan said that extending the life of Wylfa would lead to the production of more nuclear waste, and there were severe problems involved with the waste's processing.
A three-month UK Government review of Britain's future energy needs and delivery was launched on Monday.
In its own Energy Route Map published last June the Welsh Assembly Government made no reference to nuclear power.
Andrew Davies said at the time Wales needed to produce cleaner electricity without resorting to nuclear power.