French President Emmanuel Macron called for the immediate release of a jailed researcher during a long telephone call with his Iranian equivalent. French-Iranian anthropologist Fariba Adelkhah, 62, has been held in Iran since 2019. She is serving a five-year prison term over security charges that the French government described as “purely political and arbitrary”. She had been held under house arrest since October 2020 but was returned to prison earlier this month. Her supporters say authorities are deliberately endangering her health, after poet <a href="https://www.thenationalnews.com/world/2022/01/10/iran-aided-and-abetted-death-of-jailed-writer-baktash-abtin/">Baktash Abtin</a> died in custody this month after he contracted Covid-19. Ms Adelkhah, a specialist in Shiite Islam and a research director at Sciences Po university in Paris, was arrested in June 2019 with her French colleague and partner, Roland Marchal. He was released in March 2020 in a prisoner swap. She is believed to be one of at least 15 foreign or dual-national prisoners held by Tehran as pawns in wider political battles. During the phone call with Iranian President Ebrahim Raisi, Mr Macron also raised the case of Benjamin Briere, a French national who went on hunger strike after being jailed for eight years on espionage and propaganda charges. Mr Briere, 36, was arrested in May 2020 after taking pictures in a desert area where photography is prohibited and for asking questions on social media about Iran’s obligatory headscarf rule for women. France and other world powers are negotiating with Iran in Vienna to revive the 2015 deal that the country made with world powers to limit its nuclear activities in return for an easing of economic sanctions. Mr Macron “insisted on the need to speed up (negotiations) to quickly get tangible progress”, according to a statement from the French presidency. 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 prisoner exchanges in the past. Following his release, Mr Marchal said: “I realised that I was just a bargaining chip. That was quite comforting. That meant there would be an end and there would be an exchange.”