Mykola Ishchenko, who lost his 28-year-old son in the blast, said: "Safety requirements are violated there permanently.

"The system of ventilation in the shaft was not working for two days before the explosion," he said.

Stanislav Omelyanenko, a mine electrician, said at a cemetery just outside the grounds of the Zasyadko mine: "This is a mournful day for all of us. We are digging graves for our dead comrades."

Twelve miners are still missing but authorities 
say they are unlikely to be alive [AFP]
Rescuers continued to fight fires underground on Tuesday as they searched for the remaining missing miners, officials said.

Sergei Storchak, head of Ukraine's work safety agency, said: "The fire in the affected zone is continuing, but rescue workers are making progress."

But on Monday, Mykhailo Volynets, head of the independent trade union of miners, said the bodies pulled from the area where the remaining miners were believed to be trapped were burnt, indicating that others could not have survived.

"Unfortunately, there is no hope," he said.

Sunday's accident took place about 1,000 metres underground at the Zasyadko pit, one of Ukraine's biggest mines.

Accusations

The Zasyadko mine employs about 10,000 people and produces up to 10,000 tonnes of coal every day.

One miner dies at the mine for every 240,000 tones of coal extracted, the Ukrainian daily, Delo, calculated.

Viktor Gorelov, a miner who has worked at the mine for 31 years, said to the Komsomolskaya Pravda daily on Tuesday: "What happens can only be called murder."

In 1999, an explosion there claimed 50 lives, while in 2001 another blast left 55 people dead. A gas leak in September 2006 killed 13 miners.

Viktor Yushchenko, the president, who visited Donetsk on Monday, ordered a government commission to investigate the accident and called for an overhaul of the coal-mining sector.

More than three-quarters of Ukraine's roughly 200 coal mines are classified as dangerous because of high levels of methane, the concentration of which increases with depth.

Many mines are also poorly financed, employing outdated Soviet-era equipment.

Bad record

Many bodies pulled from the mine were
burnt beyond recognition [AFP]
But Andriy Klyuyev, Ukraine's deputy prime minister, said that was not the case at Zasyadko.

"This is one of the most advanced mines, and it has the most modern methods of protection against methane," he said.

"Unfortunately, the deeper the mine, the more problems we encounter."

But Sunday's blast was the fourth major accident at the mine in six years. At least 225 miners have died since 1999.

One ex-miner, Anatoly, said: "It is a terrible sight when they bring the bodies to the surface.

"They are incinerated. All but impossible to identify after death in such conditions."

Post-Soviet Ukraine's previous worst mining accident was in March 2000, when an explosion killed 80 miners at the Barakov mine near the eastern town of Luhansk.