The rescue efforts came more than a day after a fire erupted at the 105-year-old mine, killing at least 12 workers in Russia's worst gold mining accident in years.
Emergency workers recovered the bodies of the 12 miners from the Darasun mine in the Chita region 4,700 km east of Moscow on the Chinese border, state safety watchdog Rostekhnadzor said.
Fifteen out of the 31 miners who made it to the surface within hours after the blaze broke out on Thursday were hospitalised for smoke inhalation, Emergency Situations Ministry spokeswoman Yulia Stadnikova said.
Ms Stadnikova said the fire, which erupted at a depth of between 85 and 130 metres was contained that evening, but was still burning and rescue efforts were being hampered by damage and smoky conditions.
Specialised mine rescue teams were being sent to the mine amid fears their efforts would come too late.
Some were sent from Moscow as were psychologists dispatched to console relatives of dead and missing miners.
Officials initially said that the miners left underground were
OK and that most were trying to get out through a five-kilometre tunnel leading to a smoke-free shaft. But hours dragged on with no word of their fate, and later rescuers began recovering bodies.
"It got smoky. Those of us who could, there were five of us, we got out. The others are back in the mine. Other guys used emergency exits and got to the surface. The remaining are still down there.
My brother's there. I can't say any more," miner Nikolai Bronnikov said in televised comments, visibly distraught.
First deputy regional governor Vladimir Okunev said at a meeting of emergency officials that the missing miners could be still alive, and authorities were using compressors to pump fresh air into various sections of the mine to help possible survivors, the
Itar-Tass news agency reported.
About 120 rescue workers were exploring underground tunnels trying to find ways to reach the missing, the agency said.
The gold and metals mine is operated by London-listed Highland
Gold Mining PLC.
The mine has been plagued with operational problems for over a year, Dow Jones Newswires reported, badly delaying the schedule for raising output and contributing to the causes of Highland's net loss last year.
The accident "appears to be the worst in the gold mining industry in years," Rostekhnadzor spokeswoman Elena Kaliberda told The Associated Press.
Officials said earlier that negligence during welding work may have sparked the blaze at the mine, which has been in operation since 1901. Rostekhnadzor said the specific area where the accident occurred has been tapped since 1929.
Work at the mine was suspended for five years in the 1990s and some of the mine infrastructure was refurbished when it went back into operation. The last safety check was conducted in April, the agency said.
The mine produces about 450,000 tonnes of ore yielding 600 kg of gold a year, Rostekhnadzor said.