The son of former Iranian President Ali Akbar Hashemi Rafsanjani has been detained after his return from a stay abroad, Iran's official news agencies report.
Mehdi Hashemi returned to Iran on September 23 after a three-year stay in the United Kingdom.
He has been taken for interrogation to Tehran's Evin Prison, the Iranian reports say, and has been charged with corruption and antistate propaganda.
His sister, Faezeh Hashemi, was detained late on September 22 and ordered to serve a six-month jail sentence handed down to her in January following a conviction on antistate-propaganda charges.
Both Mehdi and Faezeh are accused of fomenting the protests that swept Iran following the 2009 reelection of President Mahmud Ahmadinejad.
Ex-President Rafsanjani, who was defeated by Ahmadinejad in the 2005 presidential election, is considered an isolated moderate within Iran's ruling elite.
Based on reporting by AFP and dpa