Nine people were killed overnight in unrest related to protests in the Isfahan region of central Iran, the state broadcaster reported on Tuesday.

Six protesters were killed in clashes with security forces as they tried to storm a police station in the town of Qahderijan, which has a population of around 30 000.

A member of the Revolutionary Guards was killed in nearby Kahriz Sang, and a passer-by in the town of Kahriz Sang all in the region around the cultural centre of Isfahan.

Around 100 people were arrested overnight in the same region, Iranian state television reported.

Earlier reports had already said a policeman was killed and three others injured in Najafabad after being shot with a hunting rifle.

That brings the estimated death toll to 21 in unrest linked to the protests that began last Thursday in second city Mashhad and quickly spread across the country.

The unrest has remained focused on provincial towns and cities, with only sporadic protests reported in Tehran on Monday evening.