A methane explosion was the main cause of Sunday's accident at the Karl Marx mine in Ukraine's Donetsk region, according to a statement by the country’s Deputy Prime Minister. Twenty-four men, who were trapped in the min

First Deputy PM Aleksandr Turchinov, who’s also head of the investigation committee into the tragedy, said they know exactly where the 12 miners were when the blast occurred.

“Nine were in the lift that was going up and was some 200 metres under the surface when the blast occurred. The lift was destroyed and plunged down to the bottom of the shaft, below the thousand metre level. Three others were at the bottom of the pits, and unfortunately they were buried under rock,” Turchinov said.

Turchinov said the chances of getting those people out alive are tiny. One more miner has already been found dead.

A team of 37 miners were underground when the explosion occurred and now the focus of the investigation is why these people were there, as the state-owned mine was shut down after a safety inspection just last week.

It is not clear whether those caught in the blast were repairing the safety system or whether they simply disregarded the order and were carrying on coalmining.

Ukraine's State Committee on Industrial Security says it has evidence the mine was operating illegally.

A criminal investigation into the case has begun.

Meanwhile, the miners’ relatives are demanding more information from officials.

“My son has a two-month-old child. He chose this job because there is nothing else to do here. But we still hope that he will be rescued. They've promised us they will make every effort,” said Sergey Denisenko, father of a missing miner.

It is the second accident of its kind in the region in the last fortnight. Eleven people were killed after an explosion at the Krasnoarmeyskaya-Zapadnaya mine.

In its post-Soviet history, Ukraine has lost about 5,000 people in mining accidents.

The miners, whose wages are on average about $US 600 a month, are paid piece-rate and earn nothing if no coal is produced.

The Karl Marx plant is more than a hundred years old, like many in Ukraine's mining hub of the Donetsk region. It was a loss-maker, suffered from underinvestment and had outdated safety equipment.

Many of the region’s mines stretch for more than a thousand metres below the ground, making ventilation and water pumping more difficult, and explosions more likely.

Despite calls for many of the older and deeper mines to be officially shut down, the authorities say it is impossible.

“We need these mines to carry on working in order to provide energy security for our country. To do that we have to operate at those dangerous depths,” said Turchinov.