Safety fears have shut two new ESB power plants which, between them, have the capacity to supply about 250,000 homes.

The peat-fired plants at Lanesborough, Co Longford, and Shannonbridge in Co Offaly were taken off line indefinitely after a routine check in one of them unearthed faults.

This is the second time in two years that these two power stations have been closed.

Last year Finnish group Foster Wheeler, which manufactured the plants, had to carry out repairs to both facilities after faults were discovered. An ESB spokesman said Lanesborough was shut for a routine overhaul when workers discovered corrosion on equipment used to prevent the plant from emitting sulphur into the air.

Once this was discovered, Foster Wheeler recommended that a similar check be carried out in Shannobridge. As a result of that check, the ESB decided to shut this plant also.

The power stations have the capacity to generate about 250 mega watts (mw) of electricity, enough power to supply about 250,000 homes for a year.

The ESB's spokesman said demand was low at this time of year and the closures would have no impact on electricity supply in any area of the State. He also stated that the Lanesborough plant was scheduled to be shut down in any case.

It is not clear when the plants will come back on line.

An ESB statement said its staff and Foster Wheeler's representatives were evaluating the problem. "The exact length of the outage is unclear until the results of that evaluation are known," the statement said.

The problem is not likely to cost the ESB as both plants were built within the last five years and are covered by guarantees.