The Iranian currency has hit another record low against the dollar on the unofficial market amid continued economic difficulties following the reimposition of nuclear sanctions by the United States, reports say.

The rial has lost around 15 percent of its value on the open market in the past three days, trading at 128,500 to $1 by late September 3, according to Bonbast.com, which tracks Iran's rates.

A dramatic decline of the rial, which has lost 70 percent of its value in the past year, combined with rising prices and economic hardship, have triggered protests across the country in recent weeks.

The new drop comes after Central Bank Governor Abdolnaser Hemmati on September 1 announced tighter restrictions on allocating foreign exchange reserves, according to financial journalist Maziar Motamedi.

"Hemmati said that he wishes to be much more careful in allocating foreign currencies at government rates, signaling a potential forthcoming shortage of hard currency," Motamedi told the AFP news agency.

The fall of the rial is primarily due to the country’s weak economy and heavy demand for dollars among Iranians, who fear Washington’s pullout from the 2015 nuclear deal between Tehran and world powers in May and reinstated U.S. sanctions could shrink Iran's exports.

Last month, the United States started reimposing U.S. economic sanctions on Iran that had been lifted under the nuclear accord in exchange for curbs on Tehran’s nuclear program.

A second round of penalties targeting Iran’s crude exports is due to come into effect in early November.

Amid mounting discontentment toward President Hassan Rohani’s government over a deterioration in the country's economic situation, Iranian lawmakers last week sacked the minister of economic affairs and finance, the latest in a continuing shake-up of top economic personnel in the country.