(Adds Ukraine PM/union statement)
KIEV, March 2 (Reuters) - At least eight miners were killed in a methane gas explosion in a coal mine in western Ukraine's Lviv region on Thursday, the Ukrainian emergencies service said.
The service said 34 miners had been at a depth of 550 metres when the explosion ripped through the mine at 12.46 local time (1046 GMT).
A further six miners were injured in the blast and 20 others were being brought back to the surface unharmed, it added.
Although mine safety has improved in recent years, fatal accidents are still relatively common in Ukraine's ageing pits, most of which date from the Soviet Union.
Prime Minister Volodymyr Groysman cancelled a planned meeting with German Foreign Minister Sigmar Gabriel in Kiev to fly to the area of the accident, the government's press service said.
Ukraine operates around 20 coal mines, while a further 60 are in Ukrainian territory controlled by Russia-backed separatists.