Searchers on Sunday combed wreckage at Russia's largest hydroelectric plant for six workers missing since an explosion a week ago. Three more bodies were found, raising the death toll to at least 69 people.

The Aug. 17 blast at the Sayano-Shushenskaya dam and power plant in Siberia underlined worries about Russia's decaying Soviet-era infrastructure and raised concern about long-term electricity supplies to the energy-intensive aluminum plants that are a key piece of the region's economy.

Click here to see photos.

The acting chairman of plant operator RusHydro, Vasily Zubakin, said Sunday that it would likely take three years to get the facility back in service, the state news agency RIA-Novosti reported.

The Emergency Situations Ministry said in a statement that three more bodies had been found, raising the confirmed death toll to 69. There appears to be virtually no chance that any of the six still missing will be found alive in the wreckage of the flooded turbine room.

Zubakin said the cost of rebuilding would be less than the earlier estimated 40 billion rubles ($1.2 billion), but did not give a new estimate.

The cause of the explosion remains unexplained.