Turkish Energy Minister Taner Yildiz said on Thursday that rescuers found 28 bodies of miners who had been trapped underground after a coal mine blast in northern Turkey, the semi-official Anatolia news agency reported.

The discovery came after nearly three days of search for some 30 trapped miners after an explosion hit the Karadon coal mine in the Black Sea province of Zonguldak on Monday.

"Efforts are under way to reach the other two trapped miners," Yildiz was quoted as saying.

Officials said rescuers had run into piles of debris underground caused by cave-in after the blast, delaying the rescue work.

Turkish Prime Minister Recep Tayyip Erdogan arrived at the mine on Wednesday and talked with anxious relatives of the trapped miners. He promised to exert all efforts to save the miners and support their relatives.

The cause of the accident remains unclear. Turkey's Labor Minister Omer Dincer said necessary measures will be taken once any human-related or institutional mistakes led to the accident, local media reported.

About 30 miners were working in two separate areas at a depth of about 540 meters when the explosion ripped through the coal mine on Monday, which also left another 11 miners injured, according to Anatolia.

Turkey has seen several mine accidents in recent months, with 13 miners killed in a gas explosion in a coal mine in the northwestern Balikesir province in February and 19 workers killed when a coal mine in northwest Bursa province caved in after the workers set off some dynamite last December.

In Turkey's worst mining disaster, a gas explosion killed 270 workers in Zonguldak in 1992.