Secretary of State Antony Blinken has called on Iran to release a U.S. citizen he said had been held for years as a "political pawn."
Emad Sharghi was sentenced to 10 years in prison on spying charges, Iranian media have reported, saying he was detained while attempting to flee the country.
Blinken said the Iranian-American venture capitalist had been held for four years, and that the "family has waited anxiously for the Iranian government to release Emad.
"Like too many other families, their loved one has been treated as a political pawn," the top U.S. diplomat said on Twitter on April 23.
"We call on Iran to stop this inhumane practice and release Emad," Blinken added.
Earlier on April 23, U.S. special envoy for Iran Robert Malley also called for the release of Sharghi and other detained Americans, including businessman Siamak Namazi and U.S.-British environmentalist Morad Tahbaz.
"Emad Sharghi was arrested 4 years ago today. He was cleared of all charges, but then convicted in absentia, rearrested, and has now spent over 500 days in Evin Prison," Malley said on Twitter.
"Emad, the Namazis, and Morad Tahbaz must all be allowed to come home now," he added.
On April 22, U.S. Senator Mark Rubio called for Sharghi's release, saying he remained in Tehran’s Evin prison on "false charges."
The United States, Britain, and other countries have sought to secure the release of more than a dozen dual nationals detained by Iran.
Family members and human rights activists have accused Tehran of arresting the dual nationals on trumped up charges to squeeze concessions out of Western nations.
Last month, Tehran allowed two British citizens to return home after years of detention.
Their release was reached as world leaders try to revive the landmark 2015 Iran nuclear pact.
Negotiations on renewing the deal have reportedly stalled over the U.S. blacklisting of Iran's Islamic Revolutionary Guards Corps.
