Rights groups said that Reza Valizadeh, an Iranian-American journalist, was recently arrested in Iran, although the State Department did not confirm that he was the person detained.

An Iranian-American journalist who once worked for a U.S. government-funded broadcaster is believed to be detained by Iran for months now.

"Iran routinely imprisons U.S. citizens and other countries' citizens unjustly for political purposes," the State Department said.