Rescuers, often digging with their bare hands, tried to reach possible survivors in operations throughout Sunday after a powerful explosion tore through the Taizhina mine in the Kemerovo region early on Saturday.
"The latest figure is 44 dead and three are still missing. But there is no hope of them being found alive," Sergei Kovalenko, a spokesman for the local branch of the
emergencies ministry told reporters on Monday.
Rescue teams had tried to make their way towards possibly trapped miners by both a direct route and a 5km detour through a nearby mineshaft.
But they were unable to use machinery in operations because of the risk of a fresh explosion and had to rely on the light from their headlamps as they tunnelled through earth and rock.
Several miners scrambled out after the blast. Others were pulled free with serious burns. A father and son were among those who managed to walk out.
The Kuzbass coalfield has been the scene of many accidents in the past, though Izvestia newspaper said this was the worst in the region for seven years.
The Taizhina mine is a new shaft that had been open for about four years.
Russian television described it as a modern facility in an industry flawed by lax operating procedures and old equipment. Prosecutors said they had launched a criminal investigation to establish the causes of the blast.