A French tourist jailed in Iran since last year has begun a hunger strike to protest against mistreatment in prison, his sister and his lawyer have said. Benjamin Briere, 36, was arrested in May 2020 after taking pictures in a desert area where photography is prohibited and asking questions on social media about Iran’s obligatory headscarf for women. Mr Briere was charged in March this year with spying and “spreading propaganda against the system". He began a hunger strike on Saturday after “one more mistreatment” after he was denied access to a phone call with his family on Christmas Day, his sister, Blandine Briere, told reporters. She added that Mr Briere wants to “protest … and therefore put his health at risk to move things forward”. “At the moment, we don’t see any move, we have no hope of change, of freedom,” she said. Ms Briere described her brother's “difficult” situation in the prison in the north-eastern city of Mashhad, where he endures “psychological torture”, with guards promising him a phone call and later saying no. “Physically he was doing OK [until now], but morally he has really started to sink,” she said. “It’s getting critical. It is really a desperate call for help.” A statement from Mr Briere’s lawyer in Paris, Philippe Valent, said “the feeling of abandonment and distress” has led him “to embark on a hunger strike in order to alert Iranian authorities and French authorities about the absurdity of his detention". Mr Briere has never been brought before a judge and no date for a trial has been set, the statement said. He is “not a spy nor a criminal, but a tourist whose travel is continuing in an aberrant and unfair way in Iranian prisons”, it added. The French Foreign Ministry said in a statement on Monday that French officials in Paris and Tehran have been very closely monitoring the situation and that Mr Briere has been contacted by the French embassy. There was no immediate comment from Iranian officials. Rights groups accuse hardliners 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 such prisoner exchanges in the past. In March 2020, France swapped Iranian engineer Jalal Ruhollahnejad for French researcher Roland Marchal. Mr Marchal was arrested in June 2019 alongside fellow researcher Fariba Adelkhah, an anthropologist with dual French-Iranian citizenship. Ms Adelkhah, who was given a five-year sentence for “gathering and collusion” against Iran’s security, was granted a furlough with no deadline in October 2020 and is required to stay at her sister’s house in Tehran while wearing an electronic monitoring bracelet.