PARIS -- Iran has been holding a second French researcher in custody for months, France's foreign ministry said Wednesday, denouncing the detention as "unacceptable" and demanding his release.
The confirmation that Roland Marchal is being held in Iran — as well as his fellow-academic Fariba Adelkhah — comes at a time of high tensions and diplomatic maneuvering in the Persian Gulf.
French President Emmanuel Macron has sought to serve as a mediator between Tehran and Washington over Iran's nuclear program.
Marchal, a sub-Saharan Africa specialist at Paris university Sciences Po, was arrested in June when he visited Iran to see Adelkhah, according to Sciences Po professor Richard Banegas, who has worked closely with him. The two were in a romantic relationship, according to Banegas.
It's unclear what charges the researchers face. Banegas told The Associated Press that he and colleagues consider Marchal "an academic prisoner."
Iranian authorities disclosed in July that they had arrested Adelkhah, a prominent anthropologist who holds dual French-Iranian nationality.
Marchal's detention, first reported by French newspaper Le Figaro, was previously unknown.
There was no reference to Marchal's arrest in Iranian state media.
But Iranian authorities said Monday that a third person linked to France had been arrested, exiled Iranian journalist Ruhollah Zam. The announcement by the paramilitary Revolutionary Guard did not make clear how Zam, based in France, was arrested, saying only that he was first "guided into" Iran.
The French Foreign Ministry said Wednesday that Zam was a refugee with French residence papers, had left France on Oct. 11 and was arrested abroad. But authorities had no information on the circumstances of the arrest.
Zam helped fan the flames of nationwide protests about the economy in Iran at the end of 2017 and ran a website called AmadNews that posted embarrassing videos and information about Iranian officials.
The French consul in Iran has visited Marchal multiple times in jail and is in touch with his family, ministry spokeswoman Agnes von der Muhll said.
"We want the Iranian authorities to show transparency in this affair and to act without delay to put an end to this unacceptable situation," she said.
An association of researchers at Sciences Po and other institutions said in a statement that colleagues had flagged the disappearance of Marchal and Adelkhah in Iran to French authorities on June 25. Banegas said he believed they were arrested around June 6.
The scholars kept Marchal's imprisonment confidential at the recommendation of the foreign ministry, even after Adelkhah's detention became public.
Iranian authorities have previously rejected French authorities' requests for consular access to Adelkhah because Iran does not recognize dual nationality for its citizens.
Adelkhah often traveled to Iran for her research on post-revolutionary Iranian society. Banegas said Marchal was visiting Adelkhah on a purely social trip at the time of his arrest.
Elaine Ganley in Paris contributed.