Separately, Emergencies Minister Vladimir Puchkov said that the 26 missing miners were most likely also dead.
The accident at the Severnaya mine appears to be Russia’s worst mining accident over the past few years.
On Thursday, four miners were killed and 26 went missing after a collapse at the Severnaya mine in the city of Vorkuta within the Arctic Circle.
Authorities launched a massive search operation involving hundreds of rescue workers and until now had refused to declare the missing miners dead.
But Emergencies Minister Puchkov, speaking to reporters on Sunday, said that the 26 could not have survived.
“Unfortunately, we are forced to acknowledge that all the conditions at that section of the mine would not allow a person to survive,” he said in remarks broadcast by LifeNews television channel.
He said more information would be available later in the day.
The emergencies ministry had earlier said there had been no contact with the missing miners.
Puchkov had earlier said that rescuers had risked their lives during the search operation as they had been working in tough conditions including almost zero visibility, gas-polluted air and rubble.
President Vladimir Putin has tasked the government with creating a special commission to investigate the accident.
In 2010, 91 people — both miners and rescuers — died after a methane explosion at the Raspadskaya mine in the Siberian region of Kemerovo.
In 2007, 110 people died at the Ulyanovskaya mine in the Kemerovo region, the country’s worst mining accident since the Soviet Union collapsed in 1991.