MOSCOW, July 7 (Xinhua) -- The death toll from the methane gas explosion in a nickel mine within the Polar Circle in northern Russia on Friday rose to four, the mine operator Norilsk Nickel said in a statement.
Earlier in the day, the company said the explosion killed three workers, but later the body of a fourth worker was discovered during the search and rescue operation.
"The main reason for the incident, according to preliminary data, is the unsatisfactory organization of work by the linear supervision of the Polar Construction Company, which allowed its employees to work in a mine where there was no ventilation," Sergei Gradyushko, deputy director of Norilsk's polar division, said in the statement.
Gradyushko expected that the operation of the mine will restart within hours and the accident was unlikely to affect its planned output.
Norilsk Nickel is the world second largest producer of nickel after Vale and top producer of palladium as well as a leading producer of platinum and copper. It has two main divisions in Russia located within the Polar Circle.
