Iranian police in the city of Arak in the Central Province attacked Azar Ab Industry workers during a gathering marking the second week of their walk-out Sunday October 20.
The police attacked the workers with tear gas and arrested scores of them, semi-official news agency ISNA reported.
The workers blocked the North-South railway for several hours, but the police dispersed the demonstrators and opened the railways.
Azar Ab workers have been protesting against the privatization of their work place and the non-payment of their wages for two months.
Videos posted on social media show the police firing tear gas and beating up the workers.
During the past two years, the number of cases of labor unrest for similar reasons have been on the rise in various parts of Iran.
Murky privatization deals have transferred once profitable industrial conglomerates in Iran to corrupt individuals who have used the acquired assets to borrow money from state banks and then fail to pay the workers.