The British-Iranian aid worker Nazanin Zaghari-Ratcliffe will serve out a five-year prison sentence despite demands from the UK government for her immediate release, according to Iran’s foreign ministry. Ms Zaghari-Ratcliffe is on hunger strike in prison in protest at her continued detention for what her family and supporters describe as trumped-up and political charges. Her husband, Richard, has joined the protest in support and is camped on the pavement outside the Iranian embassy in London. "Mrs Zaghari is an Iranian. She has been convicted on security charges and is spending her sentence in prison," Iranian foreign ministry spokesman, Abbas Mousavi, was quoted as saying by the state media. "Iran does not recognise dual nationality." Foreign office minister Andrew Murrison pressed Iran on Sunday for the "urgent and unconditional release" of the 40-year-old mother during a visit to Iran to discuss the situation in the Middle East. The UK’s foreign secretary, Jeremy Hunt, has taken a strong line on the issue and released photographs of himself with Ms Zaghari-Ratcliffe’s daughter when he visited Iran last year. He is currently in a two-way contest to become the UK’s prime minister with his predecessor as foreign secretary, Boris Johnson. Fears of a direct military confrontation between Washington and Tehran have risen sharply since Iran shot down a US drone last week and US President Donald Trump called off a retaliatory strike while bombers were in the air. Ms Zaghari-Ratcliffe, a project manager with the Thomson Reuters Foundation, was arrested at a Tehran airport in April 2016 as she headed back to Britain with her daughter after a family visit. She was sentenced after being convicted of plotting to overthrow Iran's clerical establishment. Mr Ratcliffe was not immediately available for comment but has previously said that she was eligible for early release. He said his wife had become a pawn in the dispute between the rival goverments and has called for her release on humanitarian grounds.