The US State Department on Friday said anything short of an immediate furlough of Iranian-American environmentalist Morad Tahbaz, who had been taken back to an Iranian prison earlier, would be considered a violation of Tehran's commitments to the United Kingdom.
Tahbaz's sister, Taraneh Tahbaz, in an interview with Reuters said her brother, who also holds British citizenship, had been taken back to prison on Friday after being released on furlough on Wednesday.
Shortly afterwards, a spokesman for Britain's foreign ministry said it had been told by Iran that Tahbaz, 66, had been taken back to Evin prison in order to fit an ankle bracelet and that the British government hoped he would be allowed out in coming hours.
A State Department spokesperson, speaking on condition of anonymity, noted that Iran made a commitment to the United Kingdom to furlough Tahbaz.
"We are not a party to this arrangement, but would join the UK in considering anything short of Morad’s immediate furlough a violation of Iran’s commitment. We are urgently consulting with the UK on appropriate responses," the spokesperson said.
"We continue to work night and day to secure the release of our wrongfully detained citizens, including US-UK citizen Morad Tahbaz," the spokesperson said.
Tahbaz was arrested in 2018 and sentenced to 10 years in prison for "assembly and collusion against Iran's national security" and working for the United States as a spy.
In February, as months of talks on reviving a 2015 nuclear deal inched closer to an agreement, Iran, which holds a dozen Western dual nationals, said it was ready for a prisoner swap in return for the unblocking of frozen assets and release of Iranians held in Western jails.
The nuclear talks were close to an agreement 11 days ago until last-minute Russian demands for sweeping guarantees that would have hollowed out sanctions imposed following its invasion of Ukraine threw the negotiations off track.
Russia now appears to have narrowed its demands to cover only work linked to the nuclear deal, leaving a small number of issues to be resolved between Washington and Tehran, diplomats say.