Thirty people have died in a series of blasts followed by a blaze that engulfed a pharmaceutical plant in central Iran, the official IRNA news agency said.

The accident occurred on Sunday when a container of chemicals caught fire.

The plant is in the Markazi province near the city of Arak, 290km southwest of the capital Tehran.

A container holding 60,000 liters of inflammable products exploded during welding work nearby and the fire quickly spread to other parts of the plant, witnesses said.

There was extensive damage within 500m of the explosion, with many vehicles destroyed and the roofs of buildings collapsing.

Many of the dead were burnt beyond recognition and 23 of the injured suffered burns of 70 per cent or more, the witnesses said.

Provincial officials said most of the factory had been destroyed but that the fire had been brought under control.

Markazi province is one of Iran's main industrial hubs.

It is also home to one of Iran's key nuclear sites, a heavy water reactor which is under construction near Arak.

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Iran map

Al-Jazeera