One of seven French detainees held in Iran is a "simple citizen of the world" who merely wanted to travel, his parents said Thursday, revealing his identity for the first time.

Louis Arnaud, 35, was arrested on September 28 as he was visiting the Islamic republic, his parents Jean-Michel and Sylvie said in a statement to AFP.

Paris says the seven French citizens are being held as "hostages" by Iran.

"Our son is neither a plotter, nor a spy, nor a villain," Arnaud's parents said, describing him as a "great traveller".

"He's a simple citizen of the world, who wants to travel to better know and understand it."

They said their son had resumed a dream of seeing the world, which was interrupted by the Covid-19 pandemic, on July 19 last year.

"Setting off from Paris, he visited Italy, Greece, Turkey, Georgia and Armenia, arriving in Iran on September 2, 2022," they said.

Since his "arbitrary arrest" on September 28 in Tehran, they said, he has been held in the capital's Evin prison, where many of those arrested in connection with the demonstrations are being held.

Arnaud's parents said he had not "taken part in any protest, nor expressed ideas hostile to Iran, its government or Islam".

They said they had not heard from him in almost seven weeks, since a brief telephone call in October and the French ambassador visited him on December 11.

"His very harsh detention conditions and the lack of communication make us fear a very heavy physical and psychological toll," they said.

Arnaud is one of two dozen foreigners who are being held in Iran, according to activists, who describe the detainees as "hostages" seized to extract concessions from the West.

The French detainees also include a French-Irish citizen, Bernard Phelan, who was detained in October and last week suspended a dry hunger strike at the request of his family.

Paris said Wednesday said that Foreign Minister Catherine Colonna in telephone talks with Iranian counterpart Hossein Amir-Abdollahian demanded the "immediate release of the seven French hostages arbitrarily detained" by Tehran.

Iran erupted into protests in September, following the death in custody of 22-year-old Mahsa Amini after she was arrested for allegedly violating the Islamic republic's strict dress rules.

According to Norway-based group Iran Human Rights, at least 481 people have been killed in the crackdown and at least 109 people are facing execution in protest-related cases, in addition to the four already put to death.