The British government summoned the Iranian ambassador on Thursday following news that imprisoned British-Iranian aid worker Nazanin Zaghari-Ratcliffe is to be recalled to court in Iran, the Foreign Office said. The British authorities conveyed their grave concern to the diplomat, Hamid Baeidinejad, and called for Iran to end what they described as Zaghari-Ratcliffes arbitrary detention. "We have made it clear to the Iranian ambassador that his countrys treatment of Nazanin Zaghari-Ratcliffe is unjustified and unacceptable, and is causing an enormous amount of distress," the Foreign Office said in a statement. A project manager with the Thomson Reuters Foundation, the dual national was arrested in April 2016 at a Tehran airport as she prepared to head back to Britain with her daughter after a family visit. She was sentenced to five years in jail after being convicted of plotting to overthrow Irans clerical establishment. Her family and the foundation, a charity that operates independently of media firm Thomson Reuters and its news subsidiary Reuters, deny the charge. Zaghari-Ratcliffe was temporarily released from jail in March in response to concerns about the spread of COVID-19 in Irans prisons, but her movements are restricted and she is barred from leaving the country. She was informed of a new charge in September, Iranian state television reported.