A methane explosion ripped through a mine in Ukraine's Donbass coalfield on Sunday, killing at least 63 miners and leaving 37 missing in underground shafts engulfed by fire and smoke.
A trade union official said there was only a small chance the missing would be found alive after the blast more than 1,000 metres (3,300 feet) underground at Zasyadko mine in Donetsk.
The figures issued by Ukraine's Emergencies Ministry put the accident among the most serious since Ukraine won independence from Soviet rule in 1991. Post-Soviet Ukraine's most deadly mining accident was in March 2000, when 80 miners were killed in an explosion at a coal mine near the eastern town of Luhansk.
Other industrial sectors in Ukraine have also been plagued by accidents causing loss of life or damage. Relatives wept, and some women screamed uncontrollably, as officials read out lists of the dead at the mine headquarters.
"I've come here to collect my grandson," said one despondent woman in her sixties. "I accompanied him to work yesterday. Now I want to take him home."
Prime Minister Viktor Yanukovich flew to Donetsk, his native region, to assess the latest of a long series of accidents in Donbass's outdated mines. He said a fire was still burning unchecked several hours after the blast.
"There is a blockage at the accident site formed by a cave-in, airshafts and water channels," Yanukovich, dressed in black, said after a meeting of a commission of inquiry. "This is being cleared."
A deputy prime minister, one of several officials who rushed to Donetsk, later said the fire was under control. Officials said 27 miners were in hospital, one in serious condition.
President criticises Govt
President Viktor Yushchenko, the prime minister's longstanding rival, announced plans to visit Donetsk on Monday. His office quoted him as saying that Yanukovich's government had "made insufficient efforts to reorganise the mining sector, particularly the implementation of safe mining practices".
Funerals were scheduled for Tuesday, and three days of mourning were proclaimed in the region. Yuri Zayats, head of Zasyadko's trade union council, said there was little hope of finding the missing alive. "The chances are small. They are poor," he said by telephone from Donetsk.
Trade unionists said the process of identifying the bodies was under way. Smoke, they said, was hampering rescue efforts. Ukrainian television showed survivors of the explosion in a hospital isolation ward.
"The temperature rose sharply -- so sharply you couldn't see anything," Vitaly Kvitkovsky told a television crew. "I put on my breathing equipment and found my way out by feeling the pipes and the rail lines."
Officials said 457 miners were underground at the time of accident. Rescue teams brought more than 350 to the surface.
The Emergencies Ministry also reported that one miner had died in a cave-in at a coal mine in Horlovka, north of Donetsk.
Accidents are common in Ukraine's coal mines, many of which date from the mid-19th century. Experts there say mining deep below the surface increases the risk of explosions.
Though Zasyadko had experienced several accidents in recent years, it is considered one of Ukraine's most modern, efficient and profitable mines upholding safety standards.
Official statistics put at 80 the death toll in mining accidents this year, though independent trade unions say the figure is higher. Last year, 170 miners died.
Accidents in other sectors have been blamed on ageing equipment, negligence or poor work discipline. A gas explosion killed more than 20 in an apartment building in Dnipropetrovsk in central Ukraine last month. In July, a train carrying phosphorous derailed in western Ukraine, causing widespread damage and prompting a mass evacuation.
"Ukraine has entered a fateful state of operating in which equipment dating from Soviet times is totally obsolete," said analyst Volodymyr Fesenko of the Penta think tank. "It is vital to update the main infrastructure urgently."