Yulia Yuzik had her passport confiscated by the police as she entered Teheran airport on 3 October and was told she would get it back on her return. She was arrested later in her hotel room by the Islamic Revolutionary Guard Corps (IRGC) for allegedly working for Israeli secret services. She faces a 10-year jail sentence.
A few years ago, Yuzil worked in Iran as a correspondent.
Yuzik, 38, has worked for a number of publications including the Russian version of Newsweek. She authored the book "Beslan Dictionary", which is based on testimony from survivors of the 2004 Beslan school massacre.
Russia's minister for foreign affairs has summoned Iran's ambassador to Moscow to clarify the reasons for this arrest .
The journalist was authorised to make one phone call following her arrest.
The Russian embassy in Tehran told AFP the mission had requested consular access to the journalist.
Secretary of the Russian Union of Journalists Timur Shafir said that the organisation was trying to contact the Iranian side in order to get information about the incident and shed light on the accusations against the journalist.
The IFJ and the EFJ are calling for a full investigation into the arrest.