Breakdowns at Viridian's gas-fired power plant at Huntstown, north Co Dublin contributed to a fall of 12 per cent in the company's operating profits in the six months to the end of September.

While turnover at the company was up to £442 million (€654 million) from £409 million, the Huntstown station suffered from two unplanned "outages" or breakdowns during the period and this reduced the profits from its subsidiary Viridian Power & Energy, which runs the Huntstown plant.

The company said that in April 2006, a failed heat shield in the gas turbine caused an unplanned outage lasting 19 days and in May 2006, the replacement of a control valve in the steam turbine restricted the station's operation for 18 days.

While this station is now operating normally, the company is constructing a similar station on the same site, known as Huntstown 2. The company said it was on schedule for completion in autumn 2007.

"Construction has progressed well. The generator and both the gas and steam turbines are now on site and the generator transformer is due to be delivered at the end of November. As at September 30th, 2006, we had invested € 46 million out of the total budgeted cost of € 250 million."

A company statement said problems at Huntstown and property sales from the same period last year were the key factors in the results. "Pro-forma operating profits were lower than the previous year due to a lower contribution from our Viridian Power & Energy businesses and the non-repetition of last year's property profits," it said.

It said that despite this, the reduction in operating profits was offset by lower interest charges and a lower current tax charge, leaving earnings per share broadly flat compared to last year.

In October, the board of Viridian agreed to a proposal from investment firm Arcapita to take over the company at a price of €2.4 billion.