Former Iranian parliamentary deputy Qasem Sholeh-Sadi has been arrested at Tehran's Mehrabad Airport, RFE/RL's Radio Farda reports.
A relative told Radio Farda on April 4 that Sholeh-Sadi was taken into custody as he returned from his hometown, Shiraz, on April 3.
Sholeh-Sadi, a lawyer, was taken to Tehran's Evin prison.
The family member said the reason for the arrest was unclear.
Sholeh-Sadi was in parliament from 1988-96. He worked recently as a professor of international relations at Tehran University's Law and Political Science Faculty.
Sholeh-Sadi was arrested in 2003 for writing an open letter to Supreme Leader Ayatollah Ali Khamenei that questioned his authority.
In the letter, Sholeh-Sadi wrote that Khamenei's appointment as supreme leader was "illegal." He also criticized Khamenei's domestic and foreign policies.
Sholeh-Sadi was charged with "insulting the authorities," "acting against national security," and "spreading propaganda to agitate public opinion."
Following the publication of the letter, Sholeh-Sadi was detained for 36 days before being released on bail in connection with serious health problems.Read more in Persian here