An Iranian scientist detained in the United States has left the country and is on his way back to his homeland, Iranian officials say, although they deny it is part of a prisoner swap.
Sirous Asgari, a materials-science professor at Sharif University of Technology, was charged in 2016 with trying to steal trade secrets from a research project being carried out by Case Western Reserve University in Ohio.
The 59-year-old Asgari, who denied the charge, was acquitted in November 2019 after a U.S. judge tossed out the case.
In a post on Instagram on June 2, Iranian Foreign Minister Mohammad Javad Zarif welcomed what he described as the "good news" of Asgari's return on a flight to Iran, and accused the United States of holding "hostage" several other Iranian scientists.
Foreign Ministry spokesman Abbas Musavi said the scientist was scheduled to arrive in Iran on June 3.
"Mr. Asgari was stranded in America for a while because of [being infected with] the coronavirus and the situation with flights," Musavi said.
His return to Iran led to speculation that he could be part of another prisoner swap.
But Musavi said that talk of a prisoner exchange was "groundless" because Asgari was "released on the basis of being acquitted."
State Department spokeswoman Morgan Ortagus later said that "Asgari is not and has never been a participant in any prisoner swap with Iran."
The United States and Iran conducted a swap in December, when Chinese-American researcher Xiyue Wang and Iranian scientist Massud Soleimani were freed.
Several other U.S. citizens are currently imprisoned in Iran or out on bail, including U.S. Navy veteran Michael White, who was temporarily released from prison in March on medical grounds amid the coronavirus pandemic.
White was arrested in 2018 and sentenced to 13 years in prison for allegedly insulting Iranian Supreme Leader Ayatollah Ali Khamenei and posting private information online.
In response to Zarif's Instagram post, acting U.S. Deputy Homeland Security Secretary Ken Cuccinelli tweeted that Asgari and White's cases had "never been related."
"We have been trying to deport Asghari since last year, being stalled every step of the way by the Iranian government," Cuccinelli added.
"We wish Iran was so enthusiastic to get its illegal nationals back as they would have us all believe," he said, adding that there were 10 other Iranians currently in the custody of the U.S. Immigration and Customs Enforcement agency (ICE).
Earlier this year, Asgari told The Guardian that the ICE was holding him at a Louisiana detention center without basic sanitation and refusing to let him return to Iran despite his exoneration.
It was later reported that the scientist had contracted the coronavirus.
Relations between Washington and Tehran have become increasingly hostile since 2018, when President Donald Trump withdrew the United States from the Iran nuclear deal with world powers.