Prime Minister Vladimir Putin on Thursday called for checks on all Russia's major infrastructure after an accident at the country's largest hydroelectric plant that left 17 dead and 58 missing. His comments at a government meeting in Moscow came as concern mounted that the authorities have yet to pinpoint the cause of the flood that engulfed the turbine room at the Sayano-Shushenskaya hydroelectric plant on Monday. 'There is a need to conduct serious inspections of all strategic and vitally important objects of infrastructure,' Putin said at a government meeting in Moscow. 'The recent tragic events at the Sayano-Shushenskaya hydroelectric plant showed with all clarity how much more we should do to increase reliability of technical constructions on the whole and hydrotechnical ones in particular,' he said. 'Technological discipline is very low,' Putin said in televised remarks. The death toll from the catastrophic flood that engulfed Russia's biggest hydroelectric power station rose to 17 on Thursday but 58 people were still reported missing, officials said. Irina Butenko, a spokeswoman for the emergency situations ministry in the Khakassia region, scene of the August 17 tragedy, said rescue workers had managed to recover three more bodies. The fate of 58 workers at the plant remains unknown, she said. 'There is so much work to do, and it's very hard,' Butenko said. She said the rescue workers have been working round the clock to clear the rubble and drain water in an effort to locate survivors. Even though robots are being used in the rescue operation, some areas are not accessible to machinery, putting additional strain on the people, she said. 'The divers have been sitting under water all night,' Butenko said. Some 2,000 rescue experts were working on the search and salvage effort at the Sayano-Shushenskaya plant in southern Siberia, according to Emergencies Minister Sergei Shoigu. Work started early Thursday 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,' Shoigu told the government newspaper Rossiiskaya Gazeta in an interview, adding that the final toll would only be clear after two to three 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, more than three days after the tragedy occurred. Meanwhile, the actual cause of the flood that swamped the turbine hall at a time when around 100 people were working inside remains uncertain, with officials saying it is too early to draw conclusions. Terrorism however has been ruled out as a cause of the disaster. 'Don't ask about possible causes. Some people have rushed to express their own opinions. Completely pointless,' said Shoigu. 'The (investigative) commission has to work everything out.' 'It's a unique disaster. Its nature is not comprehensible, nothing like this has ever been seen in the world. 'There have been many enquiries from our foreign colleagues who want to carry out a check on their own (hydroelectric) facilities so that nothing of the sort happens to them.' The official in charge of search and rescue efforts at the site of the accident, Daniyar Safiulin, was evacuated to Moscow after suffering from heart problems, but his condition was improving Thursday, officials said. The catastrophe is believed to have been triggered when a technical problem caused a massive surge of water to erupt into the turbine hall, engulfing around 100 workers. 