Nazanin Zaghari-Ratcliffe is spending her 40th birthday in prison in Iran after Tehran ignored fresh calls for her to be released.

Zaghari-Ratcliffe, a British-Iranian dual national from Hampstead, north London, has been held in Iran since April 2016, accused of seeking to overthrow the Iranian regime.

The authorities in Tehran failed to respond to an appeal by her husband, Richard Ratcliffe, and others, for her release on Boxing Day, her 40th birthday.

Zaghari-Ratcliffe, who works for the Thomson Reuters Foundation, was arrested at Tehran’s Imam Khomeini airport and later sentenced to five years in jail for spying, a charge she vehemently denies.

Jeremy Hunt, the foreign secretary, has been unable to persuade Tehran to release her.

In a video message this week, Richard Ratcliffe pointed out that Friday 28 December would be his wife’s 1,000th day in prison.

Tulip Siddiq, the Labour MP for Hampstead and Kilburn, covering Zaghari-Ratcliffe’s home area, urged the government to do more to end the imprisonment and the family’s suffering.

“For three years I’ve fought alongside Richard to free Nazanin,” she wrote on Twitter. “We’ve shared moments of joy and despair, glimmers of hope and sorrow. Today is Nazanin’s 40th birthday and she’s still jailed in Iran. How much longer will this family suffer? Our government must step up its game & bring her home.”

Hunt tweeted: “Happy 40th birthday Nazanin! Thinking of you and your family this Boxing Day. If the thoughts and prayers of a whole nation can make a difference to you and other innocent people detained in Iran then this will be last birthday you will be suffering such a great injustice.”

Profile Who is Nazanin Zaghari-Ratcliffe? Show Nazanin Zaghari-Ratcliffe is an Iranian-British dual national who has been jailed in Iran since April 2016. She has been accused of attempting to orchestrate a “soft overthrow” of the Islamic Republic. She and her three-year-old daughter, Gabriella, were about to return to the UK from Iran after a family visit when she was arrested. Since then, she has spent most of her time in Evin prison in Tehran, separated from her daughter. In January 2019 she went on hunger strike for three days in protest against being denied medical care in Tehran’s Evin prison. In March, the UK Foreign Office granted her diplomatic protection, a step that raised her case from a consular matter to the level of a dispute between the two states. Zaghari-Ratcliffe worked for BBC Media Action between February 2009 and October 2010 before moving to Thomson Reuters Foundation, the news agency’s charitable arm, as a project manager. Her family has always said that she was in Iran on holiday. Photograph: Nazanin Zaghari-Ratcliffe/PA

Hunt pressed his Iranian counterpart, Mohammad Javad Zarif, about the case in September when they met in New York on the fringes of the United Nations general assembly. The month before, Zaghari-Ratcliffe was granted a three-day release, but her request for an extension was denied and she had to say goodbye to her young daughter, Gabriella, and return to jail.

Amnesty International said Zaghari-Ratcliffe’s birthday would inevitably be a “day of anguish” rather than a day of celebration, and it called on the government to use “every channel of communication available to it” in its efforts to secure her release.

Kate Allen, Amnesty International UK’s director, said: “Her birthday will be yet another painful moment for Nazanin and her family. Despite everything, we send Nazanin our warmest wishes. She is a prisoner of conscience who should never have been jailed in the first place.”

Last week, Abbas Edalat, a British-Iranian academic and anti-war activist who had been detained in Iran returned to the UK. Edalat, a professor in computer science and maths at Imperial College London, had been held in custody since April, according to the Centre for Human Rights in Iran. Iran’s official Irna news agency reported that Edalat was held on “security charges”.