Four mineworkers were killed in accidents at two underground coal mines in Turkey on Friday, an industry official said.
In the deadliest incident, three men were killed in a methane gas blast at a privately-owned mine in the Black Sea province of Zonguldak, an official from the Turkish Hard Coal Enterprises (TTK) told AFP.
An initial police investigation found that the mine was operating illegally, the Hurriyet newspaper reported on its website.
Another worker was killed in a state-run mine in the same province when he and a colleague fell off the mine cars they were operating at a depth of 260 metres.
Explosions and cave-ins are not uncommon in Turkey's coal belt in Zonguldak, particularly in privately-run mines where respect for safety regulations is often lacking.
The worst accident occurred in 1992 when 263 workers were killed in a gas explosion in a Zonguldak mine.
And in January this year, eight miners were killed in a similar blast in the province.
According to official statistics, at least 3 700 workers have died in mining accidents in Turkey since 1941.
Last month, around 300 workers barricaded themselves in a Zonguldak mine in protest at lax safety measures and poor working conditions. - Sapa-AFP