About 30 miners remain trapped in a coal mine in Zonguldak, Turkey. On Wednesday, a mining official said it would take rescue workers four days to reach the trapped miners, dimming hopes of finding them alive.

Rescue efforts began on Monday, but obstacles make it difficult to get the trapped miners out.

The prime minister went to inspect the rescue efforts on Wednesday, amid growing concerns for the mine workers' survival chances.

Some 40 miners were reported to have been working in two separate areas at a depth of about 540 meters when the explosion occurred on Monday.

No-one has communicated with them since.

Eight workers have also been injured.

Mining disasters are common in Turkey. The worst disaster, which occurred at Zonguldak in 1992, killed 263 workers.

The Black Sea region is Turkey's largest coal producer, with output focused on coal for domestic heating needs.