Nine miners are trapped inside a salt mine in the Russian town of Solikamsk in the central Perm region.

A rescue operation is under way following an incident at a facility owned by Russian company Uralkali shortly after 10am Moscow time on Saturday morning.

Officials said the fire erupted when 17 workers were inside the mine, where the potassium-rich salt potash is dug up around 740 miles east of Moscow.

While eight of them were evacuated, nine miners were blocked by smoke following a fire. The mining company said the workers were all employees of a subcontractor doing maintenance work.

The subcontractor’s chief, Andrei Maksimov, told the Interfax news agency that the chances of finding the trapped miners alive were slim.

Rescue teams have been unable to reach the area where the workers were located because of heavy smoke.

An accident took place at the same Uralkali mining site in 2014 when a huge sinkhole opened up. The crater, found to measure 30 by 40 metres, appeared over an abandoned mine.

No-one was injured in the accident, but shares prices dropped sharply when work was briefly suspended because of the sinkhole. The company said it was caused by a large inflow of brine.