One Ukrainian coal miner was killed and at least nine others were missing, feared dead on Wednesday after a methane gas explosion at a mine in the war-scarred separatist east.
The chief health official of the self-proclaimed Lugansk People's Republic said 20 workers were inside the mine when the blast occurred on Tuesday in an area some 40 kilometres (25 miles) west of the Russian border.
"Four are in hospital getting treatment for burns. We recovered one body and nine are still under the rubble," Larisa Airapetyan told the official Lugansk separatists' news site.
"The chances of finding them alive are slim -- the gas accumulation is very high."
She did not say how or when the other six miners were rescued.
The head of the rebel region's police force said the mine had earlier been stripped of its operating license due to safety concerns.
"We issued instructions to shut down this facility, but no one listened to us," the Lugansk news site quoted police chief Igor Kornet as saying.
Local officials said the blast occurred 210 metres (690 feet) below ground.
Lugansk's separatist leader Igor Plotnitsky said on Wednesday that he had issued orders to conduct "the strictest inspections possible" of all mines in the resource-rich region to prevent further accidents.
The former Soviet republic's rust belt has suffered from repeated deadly blasts in its loss-making, poorly-maintained coal mines.
Another methane gas build up in an accident-prone mine in the rebel-held city of Donetsk killed 32 people in March 2015.
Mine safety has been hampered further by a two-year insurgency that has claimed the lives of more than 9,300 people and left few resources for crucial maintenance work.