Eight people were killed on Monday and 54 were missing when a turbine room flooded at Russia's largest hydropower station, forcing steel and aluminium plants in Siberia to turn to emergency power.
RusHydro, owner of the Sayano-Shushenskaya plant, said damage would run into "billions of roubles" and would take several months to fix. The company's shares were suspended in Russia and fell 13 percent in London.
Panicked residents in the shadow of the Soviet-era dam fled the region when news of the accident spread at 0815 local time (0015 GMT). Calm was later restored after officials said there was no danger that the dam would burst.
"There is no threat to villages downstream from the Sayano-Shushenskaya hydroelectric power station. There is no threat of damage to the dam," Emergencies Minister Sergei Shoigu said in televised comments.
Officials said water flooded a turbine room at the dam which is more than 3,000 km (1,875 miles) from Moscow in the Siberian republic of Khakassia. A spokesman for the investigative committee of the general prosecutor's office told Reuters eight people had been killed, 10 injured and 54 were missing. A RusHydro spokesman confirmed that eight had been killed, but said only seven were injured and declined to comment on the missing.
A Reuters correspondent said about 150 emergency workers in safety helmets gathered at the dam. The damaged pump room, around 100 metres in length, is located high in a concrete wall that has curved across the Yenisei river since its launch in 1978.
Vasily Zubakin, acting chief executive of RusHydro, said the plant had stopped operations and damage would run into "billions of roubles". Even a partial restart of operations would take several months, he told a conference call.
The Sayano-Shushenskaya plant represents 25 percent of RusHydro's total capacity, or 6.4 gigawatts from its total 25.3 gigawatts.
Russia's financial markets regulator ordered the suspension of trading in RusHydro shares on both Russia's main stock exchanges. RusHydro's stock had fallen 7.1 percent on the MICEX exchange when suspended, versus a wider 3 percent drop.
ALUMINIUM, STEEL
The power station is only 50 km (31 miles) from two aluminium smelters owned by United Company RUSAL, the world's largest aluminium producer and the biggest asset in the empire of indebted businessman Oleg Deripaska.
Electricity supply to the Khakassia and Sayanogorsk plants had been cut, said Dmitry Kudryavtsev, chief spokesman for the Emergencies Ministry in Siberia.
Vladimir Shulekin, spokesman for the Sayanogorsk plant, said smelters were running as normal after switching to power supplies from the neighbouring Krasnoyarsk and Kemerovo regions.
But in an emergency meeting chaired by Energy Minister Sergei Shmatko and attended by Deripaska, aluminium output cuts were discussed as a possible way of creating additional energy reserves for autumn and winter, when the load on the power system increases, UC RUSAL said in a statement.
Regional power supplier OGK-6 said in a statement it had raised output at its Krasnoyarsk hydroelectric plant to full capacity to help make up the shortfall from the accident.
Steel maker Evraz Group also relies on Sayano-Shushenskaya for some of the power used by its mills and coal mines in Kemerovo region. Evraz said it was doing everything to avoid or minimise any possible production losses.