Rescuers pumped fresh air into the smoke-choked shafts of a Siberian gold mine Friday, hoping that 21 miners were still alive a day after a fire killed at least 12 workers in Russia's latest mining disaster.

Thirty-one miners made it to the surface Thursday within hours after the blaze broke out in the 105-year-old mine, Emergency Situations Ministry spokeswoman Yulia Stadnikova said.

Emergency workers later recovered the bodies of the 12 miners, leaving 21 men still in the Darasun mine in the Chita region some 3,000 miles east of Moscow, state safety watchdog Rostekhnadzor said.

Stadnikova said the fire, which erupted at a depth of between 280 feet and 430 feet, was still burning and smoke hampered rescue efforts.

Specialized rescue teams were being sent to the mine — some from Moscow along with psychologists to console relatives of dead and missing miners.

Officials initially said Thursday that the miners left underground were alright and most were trying to get out through a 3-mile tunnel leading to a smoke-free shaft.

But hours dragged on with no word of their fate, and rescuers later began recovering bodies.

"The remaining are still down there. My brother's there. I can't say any more," said miner Nikolai Bronnikov.

First deputy regional governor Vladimir Okunev said authorities used compressors to pump fresh air into the mine to help possible survivors, the ITAR-Tass news agency reported.

About 120 rescue workers were exploring tunnels in search of 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 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.

The mine produces about 1,300 pounds of gold annually, Rostekhnadzor said.

Accidents are common in the mining industries in the former Soviet Union, where mine operators often lack funds to invest in safety equipment and technical upgrades.