The clash erupted when workers of Partex Particle Board factory in Madanpur put up a road blockade to demand hike in pay on Saturday.

Traffic on the Dhaka-Chittagong Highway was disrupted for almost one hour.

The Partex factory workers have been agitating for several days, said Bandar Police OC Akhter Morshed.

Police removed their blockade to ease traffic on the highway, he said.

Hundreds of the factory’s workers did not join work and began demonstrating at 8am, witnesses say.

They moved to the highway and set logs on fire to stop traffic.

Additional policemen were deployed at 8:30 am and they baton-charged workers when they refused to move away from the road.

The workers fought back by pelting stones.

20 were injured in the pitched battle that lasted for half an hour.

More policemen arrived at 9am to clear the highway.

Partex authorities have not immediately responded to the request for a comment.