Iranian authorities indicted a French tourist on charges of spying and spreading propaganda against the system, his lawyer said Sunday.

It was the latest in a series of cases against foreigners amid heightened tensions between Iran and the West.

Benjamin Berier was arrested in May last year after taking pictures in a desert area where photography is prohibited and asking questions “in the media” about Iran's obligatory Islamic headscarf for women.

Under Iranian law, a spying conviction can bring up to 10 years in prison and a conviction on a charge of spreading propaganda against the system can be punishable by three months to a year.

Berier's indictment was handed up by the justice department in the northeastern city of Mashahd. It wasn't immediately clear when his trial would take place.

Rights groups accuse hard-liners in Iran's security agencies of using foreign detainees as bargaining chips for money or influence in negotiations with the West.               Tehran denies it, but there have been prisoner exchanges in the past. Last year, Iran and France swapped French researcher Roland Marchal for Iranian engineer Jalal Ruhollahnejad.

Berier is the latest Westerner to be held on widely criticised espionage charges.

In March, prominent British-Iranian dual national Nazanin Zaghari-Ratcliffe reappeared in a Tehran court to face similar accusations of spreading propaganda after completing a five-year prison sentence. She remains in limbo in Iran awaiting a verdict, unable to return to London.

The cases come as Iran escalates pressure on the United States and European powers, including France and Britain, to grant badly needed relief from sanctions.

Harsh sanctions were reimposed on Iran after the US withdrew from Iran's nuclear accord with world powers in 2018.

President Joe Biden has since joined in talks aimed at restoring the deal. But Washington and Tehran have reached an impasse, with each insisting the other move first to revive the deal.