The death toll from the catastrophic flood that engulfed Russia's biggest hydroelectric power station rose to 17 on Saturday but 58 people were still reported missing.
"As a result of the disaster, 17 people have died and at the current moment the fate of 58 workers of the plant is unknown," a spokesman for the emergencies ministry's rescue operation said, quoted by news agencies.
Some 2,000 rescue experts were working on the salvage effort at the Sayano-Shushenskaya plant in the southern Siberia, according to Emergencies Minister Sergei Shoigu.
Work started early on Saturday to drain the turbine hall which was flooded by a massive surge of water in Monday's disaster, he said, in a final effort to find survivors who could still be in air pockets amid the flooded wreckage.
"My job is not to lose hope," he told the government newspaper Rossiisskaya Gazeta in an interview, adding that the final toll would only be clear after 2-3 days.
There has been mounting anger amongst relatives of the missing that the authorities have yet to give further information on the fate of the dozens still unaccounted for, over three days after the tragedy occurred.
Meanwhile, the actual cause of the flood that swamped the turbine hall at a time when 100 people were working inside remains uncertain, with officials saying it is too early to draw conclusions although terrorism has been ruled out.