Russian President Vladimir Putin has accused management of falsifying methane data at a Siberian coal mine where an explosion killed 51 people last week.
Rescuers are still bringing bodies to the surface at the Listvyazhnaya mine in Siberia's Kemerovo coal-producing region.
It was one of Russia's worst mining disasters this century.
"The management of the mine had systematically taken measures to hide the facts of excessive methane gas levels in the mine," Putin told a televised meeting with officials, citing a preliminary report given to him by investigators.
"The results of toxic gas sensors were falsified," he added.
The mine is owned by SDS-Ugol, a company controlled by local businessman Mikhail Fedyaev and his partners.
They said in a statement on November 27 they would provide payments to families of workers who had died and repay their loans.
"I am ready to bear any responsibility. It is impossible to bring people back," Fedyaev told the televised meeting after Putin asked him whether the board of directors "somehow keeps track of what is going on with safety or only counts the money".
The mine had a three-stage gas control system and portable gas analysers, but "it turns out that the human factor undercut all this," Fedyaev added.
The investigative committee and Prosecutor's Office will investigate the situation, Putin said.
Three managers of the mine suspected of flouting safety standards and two safety inspectors suspected of criminal negligence have been arrested, officials said last week.
The Kemerovo region has a history of deadly disasters.
The last big explosion killed 91 people in 2010.
Three years earlier, another blast killed 110.
"We will examine how the decisions made 11 years ago after the terrible accident, the tragedy at the Raspadskaya mine, have been implemented," Putin said referring to the 2010 blast.
"It is clear that more steps will be needed here, including of an economic nature."
Australian Associated Press