(Changes dateline, adds comments by senior official)

By Lina Kushch

YENAKIYEVO, Ukraine, June 8 (Reuters) - Thirty-seven miners were missing after a gas explosion tore through a pit in Ukraine's Donbass coalfield on Sunday, but rescuers clearing a blocked shaft still hoped to bring some of them out alive.

Officials said the blast hit the Karl Marx colliery - in the heart of the coalfield long subject to deadly accidents -- at 5 a.m. (0200 GMT) about 1 km (3,300 feet) underground. Mining operations had been suspended and repairs were being conducted.

A government minister overseeing operations said rescue teams trying to make their way through one of two damaged shafts had heard voices. There remained hope that the trapped miners could be brought to the surface.

"At the moment a rescue scheme is being worked out, with the idea being to clear the surface, the entrance to the main shaft," First Deputy Prime Minister Oleksander Turchynov told reporters at the colliery.

"When rescue teams went down the goods shift, voices were heard at about 800 metres. There is hope that people there are alive."

But Turchynov's press service said he told officials investigating the accident that rescue teams had "only a few hours" to work before the affected area would be flooded.

More than 300 rescue workers were drafted into the mining complex in Yenakiyevo, 40 km (25 miles) northeast of coalfield's main centre Donetsk, to help clear the way to the miners. The pit has been in operation for 110 years.

Turchynov said the blast was the most powerful to hit the mining industry in the memory of veteran miners.

INJURIES ON THE SURFACE

Five staff working on the surface suffered burns and other injuries after being struck by equipment tossed about the blast. Production machinery on the surface was reduced to rubble, windows were smashed and a gondola was overturned.

Dozens of distraught relatives sat in a hallway awaiting news of rescue efforts.

"My brother is underneath. I am in no way certain they will get him out," said a miner who said he had worked for 30 years.

"I know the network down there. If the shaft has collapsed you can't get to them with the elevator. No one needs the people who died here. No one needs them. We are slaves." Coal Industry Minister Viktor Poltavets hed earlier said unmanned gondolas sent underground had been unable to proceed beyond 600 metres.

Gas explosions are a frequent occurrence in Ukraine's outdated mines, many of which are unprofitable and date from the 19th century. Many coal deposits are at a depth of 1 km or more, making mining operations more difficult.

The Karl Marx mine was one of 23 where work had been suspended to check on documented safety violations and only restoration and repair work was permitted.

Officials said such work was being conducted at the colliery on Sunday and dangerous concentrations of gas had been detected shortly before the blast.

Eleven miners were killed in the last explosion in the Donbass coalfield two weeks ago. Three blasts at the Zasyadko mine in Donetsk late last year killed 106 men in two weeks. (Writing by Ron Popeski; Editing by Stephen Weeks)

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