Moscow (AFP) - Rescuers have so far failed to make contact with 26 missing miners as frantic search operations continued over a day after a pit collapse in northern Russia killed at least four workers, authorities said on Friday.
"There has been no contact with them," Tatyana Bushkova, a spokeswoman for Vorkutaugol, which owns the mine, told AFP, referring to the missing miners.
The emergencies ministry confirmed that as of 1500 GMT officials had been unable to get in touch with the missing workers in the mine located above the Arctic Circle.
"Rescue teams are trying to reach them," a ministry spokesman told AFP. "We are hoping for a favourable outcome, but the clock is ticking."
The Severnaya mine is located in the city of Vorkuta in the Komi region, which used to host one of the major Soviet-era GULAG labour camps.
In a sign of the seriousness of the situation, Russian President Vladimir Putin tasked the government with creating a special commission over the accident, the latest tragedy to hit the country's accident-prone industry.
A total of 110 people were on duty in the Severnaya coal mine at the time of the accident on Thursday at the depth of 748 metres (2,450 feet).
Eighty miners were rescued and brought to the surface. Eight were hurt and five of them remain hospitalised.
"According to preliminary information, the unforseen emergency at the Severnaya mine was caused by a sharp outburst and explosion of methane at the production unit," said a statement from Vorkutaugol, which is operated by Severstal, the Russian steelmaker controlled by billionaire Alexey Mordashov.
Hundreds of rescue workers were trying to trace the missing on Friday, the emergencies ministry said, adding that more workers had arrived at the scene with more equipment.
- Rescuers risking lives -
Emergencies Minister Vladimir Puchkov, who went to the scene on Thursday, said rescuers risked their lives by working in difficult conditions including almost zero visibility, gas-polluted air and rubble.
"This creates serious problems but we are doing our job and moving forward step by step," Puchkov said in remarks released by his ministry on Friday.
"There is a threat of repeat explosions," he said, adding that the rescue operation should continue round the clock.
Bushkova, a Vorkutaugol spokeswoman, said earlier Friday that all the places where the miners could be had been identified, adding that a fire was still burning at the site of the blast.
Vladimir Markin, a spokesman for the Moscow-based Investigative Committee, the country's main investigative agency, said that "the fate of 26 miners is currently unknown."
The Investigative Committee has opened a criminal probe into the violation of safety rules at the mine and dispatched a number of investigators and forensic experts to the scene.
The head of the Federal Service for Labour and Employment, Vsevolod Vukolov, was also sent to the remote region.
Mine accidents are fairly common in Russia and other former Soviet countries, where some infrastructure has not been modernised since the Communist era.
The explosion at the mine took place despite the fact that the company has over the past years invested heavily into safety, said Vorkutaugol.
In 2013, a methane explosion at the Vorkutinskaya mine -- also controlled by Severstal -- killed 19 people.
In 2007, 110 people died at a mine in the Siberian region of Kemerovo, the country's worst mining accident since the Soviet Union collapsed in 1991.