A sudden buildup of the gas at the Krasnogorskaya mine ignited as 66 miners were at work, and 65 were evacuated, said Valery Korchagin, an Emergencies Ministry spokesman. The extent of the burns injuries was unclear.
State television reported the Krasnogorskaya mine is one of the region's oldest, built in the 1940s, but that new safety equipment had recently been installed.
In Saturday's blast the methane accumulated so quickly it wasn't picked up by detectors in time, the Rossiya-24 news channel reported.
The mine is one of dozens in and around Kemerovo, an industrial city atop one of the world's largest coal basins. Fatal accidents are common there, with workers often ignoring
- or forced to ignore - dangerous levels of volatile gases to raise production figures.
In May, two blasts at the Raspadskaya coal mine in a Kemerovo region town killed at least 67 miners. Two dozen more are still listed as missing, presumed dead. A breach of safety rules was blamed.
Reports said that more than 1,000 safety violations had been flagged at Raspadskaya, Russia's largest coal mine, since the beginning of 2009. The head of the mine, Igor Volkov, stepped down and faces up to seven years in prison if convicted on charges of violating safety rules with fatal consequences.