A duty officer at Apatit said the blast occurred Thursday night, but would not give other details. He declined to give his name for attribution, citing company policy.
The blast occurred as 12 workers were conducting or preparing to conduct controlled explosions for tunneling, Gretskaya said. She initially said nine were killed and three missing, but later said the bodies of the others had been found.
Four bodies were brought to the surface but the recovery operation was hampered by high temperatures in the mine, Gretskaya said.
Russia's industrial safety oversight agency ruled the blast accidental, the Interfax news agency reported. Mine explosions and other industrial accidents are common in Russia and other ex-Soviet republics, and are often blamed on inadequate implementation of safety precautions by companies or by workers themselves.
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