Iranian authorities have released a French citizen held since September 2022, France's President Emmanuel Macron announced Wednesday, urging Tehran to free three other French nationals "without delay".

"Louis Arnaud is free. Tomorrow he will be in France after a long incarceration in Iran," Macron posted on X, thanking Oman in particular for helping to secure "this happy outcome".

Arnaud, a banking consultant in his 30s, was sentenced last year to five years in jail on national security charges after being arrested while travelling through Iran.

His arrest came as protests roiled Iran in 2022 over the death in custody of 22-year-old Mahsa Amini after she was arrested for allegedly violating the Islamic republic's strict dress rules.

Arnaud's family said he had "kept a distance from the social movements that were starting" at the time, adding that "At no time did he act with political intentions or carelessness".

"Louis Arnaud left the Evin prison Wednesday at dawn. He saw a doctor who cleared him for taking the plane," a French diplomatic source told AFP, adding that he was in Oman where he would be flown to Paris.

Arnaud is one of four French citizens held by Iran. The three others are teacher Cecile Kohler and her partner Jacques Paris, and a man identified only by his first name, Olivier.

In May, the French foreign ministry condemned the detention of the four s "state hostage-taking" and "constant blackmail".

"Tonight, I am thinking also of Cecile, Jacques and Olivier. I call on Iran to release them without delay," Macron said.