“Louis Arnaud is free. He will be in France tomorrow after a long incarceration in Iran,” Macron said on X, thanking Oman in particular for its role in obtaining his release.

The release is rare positive news about France and Iran.

Bilateral relations has deteriorated in recent months with Tehran holding four French citizens in what Paris has said are arbitrary arrests equivalent to state hostage taking.

France is also increasingly concerned by Iran’s regional activities and the advance of its nuclear programme.

Arnaud, who had been held since September 2022 after travelling in the country, was sentenced to five years in prison in November on security charges. He was held in Tehran’s notorious Evin prison.

“This evening, I also think of Cecile, Jacques and Olivier. I am calling on Iran to liberate them without delay,” Macron said.

In recent years, Iran’s elite Revolutionary Guards have arrested dozens of dual nationals and foreigners, mostly on charges related to espionage and security.

Rights groups have accused Iran of trying to extract concessions from other countries through such arrests. Iran, which does not recognise dual nationality, denies taking prisoners to gain diplomatic leverage.