MEZHDURECHENSK, Russia – Rescuers plunged into the dangerous rubble of Russia’s largest coal mine Monday in search of 58 trapped miners, but the head of the rescue operation said hope was dimming for finding them still alive in the city-sized maze of black and smoky tunnels deep underground.

The official death toll stood at 32 after rescuers recovered 20 more bodies from the Siberian mine that was shattered by two explosions over the weekend.

“The rescue work is continuing of course, but unfortunately the work is becoming more difficult,” Emergencies Minister Sergei Shoigu reported to President Dmitry Medvedev by video link. “Unfortunately the bodies that have been pulled out and their injuries tell us that there is less and less hope of finding anyone alive.”

Many of the dead were rescue workers who had gone into the mine after the first of the blasts. A second, more powerful blast then destroyed the main air shaft, which had a diameter of 16 feet, and a five-story building over the mine. Black soot covered the area.

High levels of methane gas remaining in the mine had raised fears of further explosions and prevented rescue workers from resuming their search until early Monday.

Shoigu said the rescuers had made it almost a mile into the mine and were hanging up oxygen tanks along the way so they would have sufficient air to make it back out. They were monitoring methane levels as they went.

A bigger danger, he said, was now posed by rising water levels deep in the mine. Rescuers have until Tuesday night or Wednesday morning to reach about a dozen people presumed to be in two locations that are being flooded, he said.

The first blast, believed to have been caused by methane, hit the Raspadskaya mine just before midnight Saturday. There were 359 workers below ground at the time and the majority managed to get out. A total of 69 people were hospitalized Monday.

The second explosion occurred about 3½ hours later, after rescuers had entered the mine.

The bodies of 12 miners and rescue workers were recovered on Sunday, the Emergencies Ministry said. A further 20 bodies — all rescue workers but one — were found on Monday.

All communication with the trapped miners was lost, Shoigu said.

Medvedev ordered the prosecutor general to determine what caused the accident at Raspadskaya. Speaking at a government meeting, the president described the mine as one of the best equipped in the country.

The mine is one of several in Mezhdurechensk, a city of about 100,000 in the coal-mining Kemerovo region of west Siberia.