Prime Minister Vladimir Putin on Friday visited the site of the Siberia power plant accident that killed 47 workers and promised compensation for their families and those of 28 others still missing.

Putin urged RusHydro, the owner of the massive Sayano-Shushenskaya hydroelectric plant, to compensate the families of the dead and missing equally. RusHydro has already pledged to pay 1 million rubles ($31,300) to the families of the dead.

Putin acknowledged there is little hope anyone could still be alive after four days in near-freezing waters.

"We can see what's happened — let's not pretend," Putin told officials in televised remarks after touring the plant, where a powerful explosion on Monday blew out walls and caused the turbine room at Russia's largest power plant to flood.

Putin promised to match the company's payouts with federal money to help families affected by this "huge tragedy."

"I've just talked to the rescue workers. They have seen it all but say that nerves fail them (here)," Putin said.

More than 1,000 rescue workers were searching the huge plant that straddles the Yenisei River. Dmitry Kudryavtsev, a spokesman for the Emergency Situations Ministry, said 47 workers were confirmed dead after rescuers found bodies in the destroyed engine room and more in another flooded room that was drained Friday.

The cause of the accident is unclear but officials cited a faulty turbine and a rise of pressure in the pipes as possible triggers.

Authorities have ruled out terrorism as a cause. However, a Chechen rebel group claimed Friday that it had sabotaged the plant by placing an explosive in the turbine room.

The statement from the group calling itself the Riyadus Salikhin Martyrs' Brigade was posted on a Web site sympathetic to Chechen rebels. The claim could not be independently confirmed.

Federal investigators later issued a statement reaffirming that experts had checked the plant for traces of explosives and found none.

Chechen rebels have a history of claiming responsibility for serious industrial accidents in Russia, but Russia's aging infrastructure has been seen as the main cause.

Putin said earlier that the Sayano-Shushenskaya accident highlighted the need to invest in critical parts of Russia's crumbling infrastructure and called for both workers and companies to pay closer attention to safety.

"In our country ... discipline in dealing with technology is very low," he said.

The plant supplies about 10 percent of Siberia's energy needs, including several major aluminum smelters belonging to Rusal, the world's largest aluminum producer. It has been shut down since the accident and could be out of service for a significant time. Repairs are estimated to take from two to four years.

Siberian electricity prices on local stock markets have skyrocketed since the accident. Putin warned about "an inevitable increase" but also suggested the government would temporarily regulate wholesale electricity prices to manage the hike.

Russian bloggers and some newspaper columnists have criticized the disaster and the rescue efforts. The country's top emergency response official, Sergei Shoigu, lashed out at bloggers, saying they were spreading panic and misinformation.

"These guys need to be punished severely," he told government newspaper Rossisskaya Gazeta.

Regional prosecutors already have confiscated the computer, mobile phone and apartment key for local blogger Mikhail Afanasyev, accusing him of slandering officials and rescuers.