Six factories in the nearby Altai region were closed down following the power crisis.

RusHydro, owner of the Sayano-Shushenskaya plant, said the generating units would be reactivated within 45 days.

'Replacing the turbine will take from 18 months to two years,' the firm's acting head, Vasily Zubakin, said. 'The station's units that were not damaged could be restarted within 45 days.'

Before the accident, 10 generating units were operating at the plant.

He said a precise assessment of the damage still needed to be carried out.

The Ekho Moskvy radio said 68 people were missing after the accident.

The Sayano-Shushenskaya hydroelectric station first started its operation in 1978.