DONETSK, Ukraine (Reuters) - Rescue teams battled a tough fire in a Ukrainian colliery on Monday as they strove to locate 28 miners missing underground after a methane blast that killed at least 72 others.

Distraught relatives awaiting news of missing miners more than 24 hours after the accident pushed their way into the office of the director to confront officials and demand information on rescue efforts and possible survivors.

President Viktor Yushchenko toured the Zasyadko pit in Donetsk, heart of Ukraine's Donbass coalfield, and chaired a session of a commission investigating the disaster's causes.

In a statement he praised the contribution of the coal industry to the country's economy, but added: "I would not want these high aims achieved at the cost of human casualties."

On Sunday, Yushchenko said the government of his longstanding rival, Prime Minister Viktor Yanukovich, had failed to reorganise the mining sector and improve its safety record. Yanukovich visited the mine in his native region on Sunday.

The explosion is one of the country's deadliest accidents since independence from Soviet rule in 1991.

Twenty-eight miners remained in hospital, one in serious condition, according to the latest figures provided by Deputy Prime Minister Andriy Klyuyev.

"The situation has become worse," Klyuyev, who heads the commission of inquiry, told reporters.

"The temperature has risen. But rescue work is proceeding. There are always chances for a rescue ... If we put the fire out, we will finish matters today."

LITTLE CHANCE FOR SURVIVORS

But trade union officials have said since Sunday's explosion 1,250 metres (3,800 feet) underground at the Zasyadko mine that there is little chance of finding survivors among the missing.

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.