Iran has detained a French tourist for nine months and his lawyers have been denied access to him, one of the lawyers, Saeid Dehghan, told Reuters on Wednesday.
The arrest comes at a sensitive time when the United States and European parties to Iran's 2015 nuclear deal are trying to restore the pact that was abandoned in 2018 by then-US President Donald Trump.
"His name is Benjamin and he is being held at the Vakilabad prison in the city of Mashhad. He was detained nine months ago and he faces contradictory and false charges," said Dehghan, who declined to give the French tourist's full name.
A person close to the family told Reuters the 35-year-old had been arrested after flying a drone in the desert near the Turkmenistan-Iran border.
French officials and his family had sought until now to keep the information secret due to the current disputes in the region, fearing it could harm potential negotiations.
Iran's judiciary was not available to comment. France's foreign ministry confirmed that a French citizen was being held in Iran, adding that it was monitoring the situation.
It said the French citizen benefited from consular protection and that embassy officials had been in regular contact with him.
The person close to the family said Benjamin, who works in the events industry, had travelled to Iran by van from France. He is in good health and has been in contact with the family three times since his arrest last May, including twice in the last few weeks, the person said.
Iran's Revolutionary Guards have arrested dozens of dual nationals and foreigners in recent years, mostly on espionage charges, including Franco-Iranian academic Fariba Adelkhah, whom Tehran sentenced to six years in prison in May 2020 for security-related charges.
However, her partner, French academic Roland Marchal, who was detained along with her, was released last year. Marchal was freed after France released Iranian engineer Jalal Ruhollahnejad, detained over alleged violations of US sanctions against Tehran.
Rights activists have accused Iran of arresting dual nationals and foreigners to try to win concessions from other countries. Tehran denies it holds people for political reasons and has accused many of the foreigners in its jails of espionage.
Adelkhah was released on furlough last October. Dehghan, who is also Adelkhah's lawyer, said she had been under house arrest since then.
"Of course, Adelkhah is wearing an ankle monitor which limits her movements to 300 m (985 feet) from home," Dehghan said.
French Foreign Minister Jean-Yves Le Drian, in a speech to the UN Human Rights Council on Monday, called for Adelkhah's release. Tehran, which does not recognize dual nationality, has rejected France's calls to release Adelkhah.
The United States has signaled it is ready to talk with Iran and global powers, including France, about how both nations could return to the 2015 agreement that aimed to prevent Tehran from acquiring nuclear weapons.
President Emmanuel Macron has previously tried to mediate between longtime foes Iran and the United States and said last month he was ready to resume that role.