Iran has put on trial a French citizen and a local employee of the French embassy in Tehran, according to the semi-official Fars news agency.
Clotilde Reiss, held in Tehran's Evin Prison, was arrested at Tehran airport on 1 July on charges of espionage when leaving the country after spending five months as a French language teaching assistant in the city of Isfahan.
France has rejected the charge against Ms Reiss as "baseless" and French President Nicolas Sarkozy has called for her immediate release.
The French Foreign Ministry said on July 15 that a French-Iranian woman, working for its embassy in Tehran, had been detained for three days by the Iranian authorities.
Defeated presidential candidates Mirhossein Mousavi and Mehdi Karoubi, both moderates, say the June vote was rigged in favour of hardline President Mahmoud Ahmadinejad, who was sworn in on Wednesday.
The authorities deny the charge, saying it was the "healthiest" vote in the past 30 years.
Two groups of people have now been put on trial over the post-election unrest.