Ali Reza Jamshidi, a spokesman for the Iranian judiciary, also told CNN another Iranian-American, sociologist Kian Tajbakhsh, has been detained. Jamshidi said Tajbakhsh is under investigation on the same charge as Haleh Esfandiari. Both are being held in Evin Priosn.
Esfandiari works for the Woodrow Wilson Center for Scholars in Washington and went to Iran to visit her mother. She has been in custody since May 8, while Tajbakhsh, who works for the Open Society Institute, was picked up two days later.
Human Rights Watch said at least three Iranian-Americans have been arrested or had passports confiscated recently. A fourth, Parnaz Azima, a reporter for Radio Free Europe, has had her passport confiscated and has been warned she may face a criminal charge.
A retired FBI agent, Robert Levinson, disappeared in Iran in March.