Torness nuclear power station was affected when nearby pylons were struck during storms in May, causing a power surge which put one of its two reactors out of service.

British Energy, which owns the East Lothian plant, is consulting lawyers over the possibility of suing electricity supplier ScottishPower over the incident.

The incident is thought to have cost British Energy about £500,000.

The lightning strike happened during storms

British Energy executive chairman Robin Jeffrey said: "We are in the middle of legal discussions and I wouldn't want to comment further."

A spokesman for ScottishPower said the issue was a "minor legal dispute which we hope will be resolved in due course".

Torness was shut down completely earlier this week after one of the gas circulators which cools the reactors started vibrating.

However, the company insisted the closure was unrelated to May's lightning strike, which it described as "very unusual".

Shares in British Energy slumped 30% on Tuesday, wiping £160m of the firm's total value, in the wake of the shutdown.

A company spokesman said there was no timetable for the resumption of power generation at the plant, adding it would remain closed "for the foreseeable future."