Post-Soviet Ukraine's worst mining accident was in March 2000, when 80 miners were killed in an explosion at a coal mine near the eastern town of Luhansk.
Weeping relatives spent Sunday night at a park adjacent to the Zasyadko mine.
By mid-morning, more than 100 made their way into the colliery's administrative headquarters and burst into the office of the mine director where Klyuyev was chairing a meeting.
"We demand at least some sort of information!" shouted Olga, in her 50s, her face ashen. "We've been waiting for more than 24 hours and all we get is promises. No one is telling us anything."
Officials read out a list of identified victims. Klyuyev told relatives the fire was hampering rescue work and that officials were doing their best to keep relatives informed.
The group left the office within half an hour, with medics attending to several clearly under stress.
Miners at the pit, one of Ukraine's most profitable in a sector plagued by obsolete equipment, earn wages equal to about $1,000 a month, more than three times national average pay.
Many miners were openly shaken by the accident which sent fire and smoke roaring through underground shafts.
"After an accident like this, lots of miners quit and I'm thinking about it too," said one identifying himself as Nikolai. "Why should I do this? I live alone with my daughter. What happens if I end up getting killed?".
Others seemed resigned to sticking to their jobs in the pit.
"I don't know how to do anything else," said Yevgeny. "I earn more than 4,000 hryvnias ($800) and I have four children. I have to keep them fed."
Other industrial sectors in Ukraine have also been plagued by accidents causing loss of life or damage -- including the derailment of a train carrying phosphorus in July and a gas explosion killing 20 people in an apartment block last month.
