Iran’s Foreign Minister Mohammad Javad Zarif said on December 9 that Tehran is ready for more prisoner exchanges with the US, days after the two foes exchanged two of their detained nationals.

"After getting our hostage back this week, fully ready for comprehensive prisoner exchange," Zarif tweeted, adding: "The ball is in the [U.S.'s] court.”

His remarks came as the Iranian rial (IRR)—battered in the past year and a half by the US decision to hammer Iran with sanctions to try and force Tehran to accept a toughened up nuclear deal—reached its weakest level against the dollar in six months, trading at just above 120,000. A 15% drop started with widespread anti-regime protests that began on November 15 after a sudden petrol price hike. Progress in swapping prisoners could conceivably lead to a slight thawing of relations that just might open the door to some progress in resolving the standoff between Tehran and Washington.

The December 7 prisoner exchange between the US and Iran involved Xiyue Wang, a Princeton graduate student detained by Iran on widely dismissed espionage charges, and Masud Soleimani, an Iranian scientist held by the US for violating sanctions against Iran.

Also on December 9, official Iranian news agency IRNA quoted Iranian government spokesman Ali Rabiei as saying Tehran had always sought an "all-for-all release" with the US.

Rabiei said efforts to swap prisoners were not linked to any other US-Iranian talks. Such talks, he said, would only become possible if Washington lifted sanctions against Iran and returned to the 2015 nuclear accord between Tehran and six world powers that the US unilaterally abandoned in May last year.

In October, Iran said it had given the US a list of 20 Iranians held in US prisons on charges of circumventing sanctions.