Performance woes add to safety fears at power station

The East Lothian station is also at the centre of safety fears after documents released by the Nuclear Safety Directorate showed that British Energy's Torness and Hunterston B plants have serious flaws. Hunterston B reportedly has damage to its reactor core, while it is thought Torness has similar problems, sparking fears of a major radiation leak.

Meanwhile, British Energy, which meets a fifth of the UK's energy needs, announced an 85 per cent rise in profits to GBP 215 million in the last quarter because of rising electricity prices.

But a warning came that output targets could be missed due to a growing number of unplanned stoppages.

More than 200 incidents at Torness saw output losses leap from six per cent to 34 per cent - the highest in the UK. Losses at Hunterston rose, meanwhile, from 10 per cent to 18 per cent.

British Energy chief executive Billy Coley said the losses were disappointing. He added: "We are continuing to focus on improved reliability."

Friends of the Earth Scotland warned the faults at the sites increased the risk of a major incident.

Green MSP Mark Ruskell said: "The profits are artificial but the safety issues are very real. Nuclear power is unreliable, uneconomic and unsafe.