Turkey declared three days of mourning on Wednesday as the death toll from a mine explosion and fire reached 201.

Flags were lowered to half-mast around the country and at diplomatic missions abroad, the office of Prime Minister Recep Erdogan said.

However, up to 300 people were still trapped underground, officials said.

A total of 787 were said to have been in the mine during a change of shift when the fire broke out late on Wednesday.

Six people were pulled from the mine 18 hours after the accident, news reports said on Wednesday.

The fire, thought to have been caused by an electrical malfunction, was still burning early on Wednesday, Energy Minister Taner Yildiz said.

Earlier reports said the blaze had been extinguished.

Erdogan was to visit the site of the accident at Soma, in Manisa province, about 230 kilometres south of Istanbul, after cancelling a planned foreign trip.

The trapped miners are believed to be about two kilometres below the surface and four kilometres from an exit, hampering the rescue effort.

Mine operator Soma Holding said a safety test was carried out two months ago.

Local media reported that the ruling Justice and Development Party rejected a call by the opposition in parliament last month to review safety at the Soma mine.

Turkey has a history of deadly mining accidents, in part owing to poor safety regulations, including one in 1992 near the Black Sea which left more than 260 people dead.