Tehran’s Grand Bazaar has reportedly closed as authorities crack down on black-market currency traders in the Iranian capital with the rial plummeting against the dollar.

Witnesses told RFE/RL’s Radio Farda and Western news agencies that riot police had clashed with protesters angry over the collapse of the currency, which has lost more than one-third of its value in less than a week.

Tehranis earlier in the day told Radio Farda that Iranian police were arresting unlicensed money changers there.

Iranian officials have blamed “psychological pressures” from Western foes for the decline and currency traders, calling them speculators who should be detained by security officials.

The U.S. State Department says the rial’s decline is the result of U.S.-led international sanctions imposed over Tehran’s disputed nuclear program.

Economists say poor management by Iranian President Mahmud Ahmadinejad’s regime also is contributing to the rial’s rapid decline.

Some currency dealers in Tehran said the rial traded at about 40,000 to the dollar early October 3 — down from 37,500 one day earlier and about 24,500 early last week.

The value of the rial has fallen more than 80 percent since the start of 2012.

With additional reporting by AFP and Reuters

By RFE/RL