According to AFP, three unidentified workers were underground at the Turkish Hard Coal Enterprises operation in the Zonguldak province when a methane gas explosion hit the privately owned mine.
The country’s Hurriyet newspaper said the mine was illegally operated.
In a second incident, a fourth unnamed miner was killed at a state-run mine in Zonguldak.
The mine was not identified but officials told AFP that the victim and another person fell from transport cars about 260m underground.
According to Turkish statistics, about 3700 miners have been killed on the job since 1941.
One of the most recent was a September mine collapse that killed three in Sirnak, southeast Turkey. The youngest victim in that incident was just 18.
The worst accident in the country occurred in 1992 in Zonguldak, when 263 workers were killed in a gas blast.
