The plant is one of four earmarked for closure in June 2008 under a deal brokered with the Commission for Energy Regulation (CER) aimed at reducing the ESB's dominant position in the Irish power generation market.

The station last underwent a major overhaul just three years ago following a fatal explosion which killed two workers in July 2003.

An ESB spokesman said that the "smallish overhaul" on one of the station's four generation units was essential.

"We're going to be running this plant up to 2010 and you need periodic overhauls to meet health and services and insurance requirements, " he said.

"What we would not be doing, however, is conducting any major investment in plant due to its imminent closure."

But he added it was likely other units at the plant would also undergo refurbishment work in future years.

The spokesman said this should not be interpreted as any indication that the ESB was willing to sell the plant and the three others planned for closure.

Industry sources believed, however, that the ESB has no intention of shutting Tarbert and the other stations but would try to find buyers for them.

The buyers would probably run the plants for around five years, close them and then redevelop the sites.

"The ESB would probably like to sell them as going concerns but the independents are worried because they'll be dependent on the existing staff and work practices at them, as well as outdated technology, " said one prominent industry figure.

ESB sources have indicated that the company has received no approaches for the stations but it is believed that German energy giant Eon, which is conducting the refurbishment work at Tarbert, Viridian and Bord Gais are among those potentially interested in them.