The bodies of at least 21 miners trying to help colleagues trapped after an explosion in a coal mine in northern Iran have been recovered, state media has reported, the BBC reports.

A local official in the area said that nearly 70 people were injured.

The officials said that those killed were miners in a tunnel trying to reach 32 miners trapped underground in the northern province of Golestan.

The mine blast is thought to have been caused by a gas leak.

Emergency crews are at work at the scene of the disaster, and have so far cleared about 600m of the tunnel leading to the mine, officials say.