The death toll from a mine disaster in northern Russia has risen to 36, making it the country’s worst ever mining accident.

The disaster began on Thursday, when two explosions took place at a depth of 780 meters at the Severnaya mine in the Komi region. Officials say that a sudden leak of methane gas caused the blasts.

Four miners were killed and 81 other managed to flee to ground level.

On Sunday, Tatyana Bushkova, a spokeswoman for the mine's operator Vorkutaugol, said that 26 people who were trapped in the mine following Thursday’s operations died.

She also said that rescue operations were halted following a fresh methane explosion at the mine. Five rescue workers and a miner were killed.

Russian officials in Komi region declared three days of mourning for the victims of the incident.

President Vladimir Putin tasked a government panel to probe the incident. The panel opened a criminal inquiry into any violation of safety rules and sent investigators to the mine to explore the reasons behind the blasts.

Mine accidents are common in Russia, where poor safety standards have been blamed for such incidents.

In 2010, a methane blast rocked the Raspadskaya mine in Kemerovo region in Siberia, killing 91 people, including rescuers.

Some 110 people died in another mining disaster at the Ulyanovskaya in Kemerovo mine in 2007.