France has confirmed that a second French academic is being detained in Iran, condemning what it described as "an unacceptable situation."
Roland Marchal was arrested in June, at the same time as Fariba Adelkhah, a dual French and Iranian citizen, France's Foreign Ministry said Wednesday.
Both are senior researchers from Paris's prestigious Sciences Po university. It was previously known that Adelkhah had been taken into custody, but the ministry had not confirmed Marchal had been detained as well.
It was not clear what crimes the academics are accused of.
French Foreign Ministry spokeswoman Agnes von der Muhll urged the Iranian authorities to "show transparency in this dossier and act without delay to end the unacceptable situation."
Marchal's arrest had not been made public as the French authorities were seeking to work discreetly for his release, reports said.
Marchal has received consular visits and has a lawyer, von der Muhll said.
In an email sent to students, Sciences Po's management denounced his "arbitrary, scandalous, and revolting" arrest.
Marchal and Adelkhah are said to be held in Tehran's Evin prison.
French newspaper Le Figaro and Reuters first reported Marchal's detention on October 15.
Tehran has called the detention of Adelkhah, a 60-year-old anthropologist, an internal affair, and refused to offer her consular access, insisting that it does not recognize dual nationality for its citizens.
The arrests of the two French citizens could complicate President Emmanuel Macron's efforts to ease tensions between Washington and Tehran.
Last week, France's Foreign Ministry warned French citizens against traveling to Iran, citing "regional tensions" and "arbitrary arrest and detention practices from the Iranian security services."
Iran has arrested dozens of dual nationals in recent years on alleged espionage charges.
Iranian authorities have not provided any evidence to back their claims.
