The dollar was being offered for as much as 170,000 rials, according to Tasnim. The rial has lost approximately 75 percent of its value since the beginning of 2018.

The currency has been volatile for months because of a weak economy, financial difficulties at local banks and heavy demand for dollars among Iranians who fear the pullout of Washington from a landmark 2015 nuclear deal and renewed US sanctions could shrink Iran's exports of oil and other goods.

A set of US sanctions targeting Iran's oil industry is due to take effect in November. Rouhani, in a speech to the United Nations General Assembly on Tuesday, said the United States had waged "economic war" against Iran by reimposing unilateral sanctions.

Iran's parliament sacked the minister of economic affairs and finance and the minister of labour in August, the latest in a continuing shake-up of top economic personnel. In July President Hassan Rouhani replaced the head of the central bank.

Protests linked to the tough economic situation in Iran erupted last December, spreading to more than 80 cities and towns and resulting in 25 deaths.