Thousands of retail businesses in Iran went on a general strike Monday after underground activist groups called for three days of protests and market closures.

The three-day period started on Monday and will end on Wednesday. Nationwide protests are also expected to start Monday afternoon, while the authorities have run out of options to subdue the protesters, after resorting to deadly violence since mid-September.

Reports say businesses in over 40 cities across Iran are on strike with over 90 percent of retailers shutting their doors in a move that will be costly for the already beleaguered economy.

Tehran, Rasht, Karaj, Esfahan, Shiraz, Ardebil, Dezful are the main cities observing the shutdown to step up pressure on authorities.

Similar calls for strike action and mass mobilization in past weeks have strengthened the protest movement and led to a political crisis for the regime.

Workers at oil industry sector have also expressed support for the three-day call saying that all imprisoned workers, teachers, students must be released as soon as possible.

In universities, students have gone on strike to join the three-day movement that has called for the overthrow of the Islamic Republic.

Nearly 500 people have been killed in the unrest that erupted in September after the death in custody of Mahsa Amini, a 22-year-old woman who was detained by ‘morality police’ for breaking hijab rules.