About 52 miners were working at a depth of 1,300m at the Skochinsky mine when the accident occurred, Reuters reported.
One other miner was injured and taken to hospital.
Ukraine Energy Minister Yuri Prodan told parliament in the capital Kiev that there had been violations of safety regulations.
An inquiry has been formally opened by the prosecutor general’s office into the circumstances of the explosion.
A similar accident took place at the same mine in June 2010, killing two miners.
In February 2014, seven miners were killed and nine injured at Pivnichna coal mine at the in Ukraine’s mineral-rich Donetsk region, following a methane blast.
