As the rescue operations continue in the Zasyadko coalmine in Donetsk, Igor Krol, chief spokesman of the Emergency Situations Ministry announced “the death toll has climbed to 63 and the fate of 37 others is still unknown”

The blast took place early Sunday at a depth of 1,000 meters in the Zasyadko coalmine in Donetsk, the main town of Ukraine's eastern coal-rich region. The Zasyadko mine employs some 10,000 people and produces up to 10,000 tones of coal every day.

The death toll was initially reported to be 17. Ukraine's Vice Prime Minister Andry Kliuev confirmed that 26 miners have been hospitalized by now, one of them was injured seriously, and others were diagnosed with gas poisoning.

According to the Interfax news agency, over 10 hours after the methane explosion, the fire at the mine was still not under control.

"Efforts are under way to extinguish the fire. After that, rescuers will begin their work," Kliuev said.

At the time of explosion 457 miners were working underground and over 350 workers had been rescued after the accident.

According to the Ukrainian media reports, the affected mine shaft had been the scene of numerous methane gas explosions in which dozens have been killed. Ukrainian mines are amongst most dangerous in the world and a third of 165 mines are over 100 years old. Most mines have not been overhauled and brought up to date for decades even though the Ukrainian government has demanded increased extraction of coal.

From January to July 2007, 150 miners died in accidents and nearly 6,000 were injured, and the country's mines saw 170 fatalities during 2006. In 2002, an explosion killed 20 and 54 died in a similar explosion in 2001.

Methane gas discharges, explosions, shaft collapses, and digging machine failures - almost always aggravated with poor safety procedures - are the most common causes of the accidents.

Prime Minister Viktor Yanukovich, a native of the mining region, had earlier visited the scene of the accident and said: "We have to build new mines and we are building them, but not yet enough”. He accused the government of "not doing enough to reorganize mining". Three days' mourning were ordered in the region, beginning Monday. "I am grieving with all of Ukraine," President Viktor Yushchenko said in a statement.