Vladimir Putin, the Russian president, ordered his emergencies minister to fly to the Ulyanovskaya mine, in the Kemerovo region, to oversee the rescue effort.
"The main task now is to find as many people as possible," Aman Tuleyev, Kemerovo governor, said in footage broadcast by the Rossiya television station.
Television pictures showed rescue workers in breathing apparatus walking down a shaft into the pit.
They also showed one miner, his clothes black with dirt, lying motionless on a stretcher as emergency workers transferred him to ambulance.
The Ulyanovskaya mine was opened in 2002, making it unusually new by the standards of Russia's mining industry.
Vladimir Berdnikov, head of the Siberia branch of the emergency situations ministry, said rescue work was difficult.
|Medics provide help to a survivor at a hospital|
in Novokuznetsk in Siberia [Reuters]
"Work underground is taking place in difficult conditions," he said.
Rescue officials said attempts to reach the trapped miners were being hampered by thick smoke and because sections of the roof had collapsed.
At the entrance to the mine complex, security guards prevented reporters from getting close. Ambulances and rescue vehicles were driving to and from the site, a photographer at the scene said.
The blast was the deadliest in a long line of fatal accidents in Russian mines, many of which are several decades old and lack modern equipment.
Last year, 25 Russian miners died in a fire at a gold mine in eastern Siberia. A gas explosion at a coal mine in Kemerovo in 2004 killed 45 people.
The mine belongs to the Yuzhkuzbassugol company, in which Russia's second-biggest steelmaker, Evraz, holds a 50 per cent stake.
Yuzhkuzbassugol's management owns the other 50 per cent and has operational control of the company.