Iran has accused a French couple detained in May of "undermining the security" of the country.
The pair stand "accused of association and collusion with the aim of undermining the security of the country", judiciary spokesman Massoud Setayeshi told reporters in Tehran on July 6.
French teachers' union official Cecile Kohler and her partner, Jacques Paris, were arrested in early May in Tehran while on vacation sightseeing in the Islamic republic. They are accused by the authorities of seeking to stir up labor protests.
Iran said they were accused of "entering the country to sow chaos and destabilize society."
The French government has condemned their arrest as "baseless" and demanded their immediate release.
"These two people are currently in police custody," Setayeshi said, adding that "the prosecution is dealing with this case."
In June, Iranian authorities announced they had arrested a left-wing activist on suspicion of working to "incite sedition and turmoil among the working class," and who they said was suspected of meeting the French couple.
Teachers have in recent months taken to the streets on several occasions to protest their conditions and demand higher wages. They have also called for the release of their jailed colleagues.
In April, a court sentenced Rasoul Bodaghi, a member of the teachers' union and a civil activist, to five years in prison after convicting him of illegal assembly and propaganda.
The New York-based Center for Human Rights in Iran said Bodaghi had been sentenced solely for "peaceful activism."
Kohler and Paris are among the latest Western citizens to be detained in Iran.
Western countries and rights groups have repeatedly charged that Iran is trying to take advantage of foreign countries by taking dual and foreign nationals hostage.
