More than 50 miners were trapped after a huge explosion in a coal mine in northern Iran on Wednesday, and some were feared to have died, state media reported.

The reports said more than a dozen injured people had been transferred to hospital after the blast at 12:45PM local time in the Zemestanyurt coal mine in Golestan province.

State news agency IRNA quoted a local official as saying some of the trapped miners may have died in the explosion. A rescue operation was under way.

Iran extracted 1.68 million tons of coal in 2016, an increase on previous years, thanks to an easing of international sanctions. It exports only a fraction of the coal and uses most of it in domestic steel production.