Iranian riot police have been deployed at key intersections in Tehran after tensions flared over the nation's plunging currency in the most widespread display of anger linked to the country's sanctions-hit economy.

Shops in Tehran's main bazaar were reopened on Thursday, the first day of the Iranian weekend, and no unrest was reported.

Still, the show of force by police reflects the authorities' concerns in the wake of sporadic protests from the plummeting currency, which has sharply driven up prices.

Many bazaar merchants closed their shops on Wednesday and authorities reported arrests amid efforts to clampdown on black market money exchangers, who effectively set the rates around the country.

Iran's rial has lost nearly 40 percent of its value against the U.S. dollar in the past week.