The Donetsk regional administration reported in a statement that 17 bodies had been recovered from the Zasyadko mine following an explosion early Wednesday.

Throughout the day, contradictory reports about the number of casualties had been issued by authorities loyal to either the Ukrainian government or to the pro-Russia separatists who control the Donetsk region.

Mine officials said the blast at more than 1,000 meters (3,280 feet) underground was most likely caused by methane gas mixing with air, a common cause of industrial mining accidents. They did not link it to fighting on the nearby front line in the war between the separatists and Kyiv's forces.

In total, 230 workers were reported to be underground when the explosion occurred. Anxious relatives gathered near the mine, concerned for their loved ones.

"We have no information, I fear he's dead," a tearful Valentina Dzyuba told the Agence France Presse (AFP) news agency as she waited for news of her 47-year-old son Vladimir.

Help rejected?

In Kyiv, Ukrainian Prime Minister Arseniy Yatsenyuk said the separatists had prevented a team of 60 Ukrainian rescue workers from reaching the mine to help.

Leading separatist representative Denis Pushilin was quoted by the Associated Press (AP), citing the Donetsk News Agency, as denying help had been offered and saying they would turn to Russia if assistance was needed.

The Zasyadko mine, in the heart of Ukraine's Donbass industrial and coal-producing region, has a history of deadly accidents. In 2007, an explosion there killed more than 100 people.

Eastern Ukraine has been blighted by fighting between pro-Russia separatists and forces loyal to the Ukrainian government since April 2014. The United Nations estimates more than 6,000 people have been killed so far in the violence. During the past week, a ceasefire has been in place but the situation remains volatile.

se/lw (Reuters, AP, AFP, dpa)