We need special equipment because the fire is very deep down

Mykhailo Klyagin Rescue worker

But there are reports that the rescue workers have halted the search, as the fires continue to rage near the scene of the blast about a kilometre (half a mile) from the surface.

Officials said 259 miners were underground at the Zasyadko mine when a mixture of coal dust and methane gas exploded on Sunday morning.

Fear of flooding

Rescue workers have been unable to get closer than within some 100 metres (100 yards) of the blast scene because of temperatures of 60-80 degrees Celsius (140-176 Fahrenheit).

39 miners remain in hospital

"We need special equipment because the fire is very deep down," said Mykhailo Klyagin at the Donetsk Rescue Workers Centre.

Salvage teams have been unable to use water to douse the flames for fear of flooding the mine shaft.

Rescuers now planned to pump the shaft with a gaseous compound to extinguish the fire, safety department officials said.

Experts say that the fire could rage underground for months if not properly put out.

Death toll uncertain

Overnight rescue workers pulled out 17 bodies, union chief Yuriy Zayats and police guarding the mine said.

These accidents are happening more and more often

Ivan Misyura, Independent Coalworkers Union

That was in addition to about a dozen recovered on Sunday.

The regional safety department and the Emergency Situations Ministry have put the death toll at 36, although reports from the various rescue teams has made compiling an exact total difficult.

Thirty-nine people remained in hospital on Monday, most with severe burns, the regional Worker's Safety Department, which oversees investigations into mine accidents, said in a statement.

Survivors who had been working in another shaft described three explosions in quick succession, though officials described one large blast.

Anxious relatives

The atmosphere outside the mine is said to be subdued as exhausted rescue workers wait alongside anxious relatives, who are remaining at the mine hoping for news of their loved ones.

Meanwhile other miners continue to work in other shafts at the mine.

President Leonid Kuchma headed to Donetsk region on Monday to review the rescue effort and investigation into the accident.

Officials have said that it is too early to speculate on the cause of the accident and a special commission to investigate the incident has been set up.

Ukraine's mines are considered among the world's most dangerous.

Outdated equipment and widespread disregard for safety rules have been blamed for the accidents, which claimed 318 lives last year, and at least 140 so far this year.

"These accidents are happening more and more often," said Ivan Misyura, head of labour relations for Ukraine's Independent Coalworkers Union. "Salaries are bad, safety controls are bad."