Prime Minister Theresa May was today set to personally petition for the release of Hampstead’s Nazanin Zaghari-Ratcliffe, who remains in Iran’s Evin prison.

Ms May is at the United Nations general assembly in New York, and she is expected to meet Iranian President Hassan Rouhani and to raise Nazanin’s case.

The Prime Minister will make clear her “serious concerns” about the detention of Nazanin Zaghari-Ratcliffe and urge the Iranian leader to free her on humanitarian grounds.

Hampstead and Kilburn MP Tulip Siddiq welcomed Ms May’s intervention. She tweeted: “3 weeks ago I publicly asked the PM to raise the case of my constituent Nazanin with President Rouhani at the UN general assembly.

“It looks like she’s doing so. Never thought I’d say this but thank you Theresa May. Please help us bring Nazanin home. #FreeNazanin” A senior Government official said: “The PM will express serious concern at Nazanin’s on-going detention and call for her to be released upon humanitarian grounds.”

Nazanin has been in jail since 2016, and her daughter Gabriella, 4, has been stranded in Iran with her grandparents for more than two and a half years.

Last month she was granted a three-day release from Evin prison on furlough, but her request for an extension was denied and she was forced back to prison.

She subsequently suffered several panic attacks, while husband Richard Ratcliffe wrote an open letter to Iran’s foreign minister Javad Zarif calling the short release a “cruel game”.

Director of Amnesty International UK, Kate Allen, said: “This is a step in the right direction, and we welcome the news that the Prime Minister will personally address Nazanin’s plight tomorrow.

“Nazanin’s detention has gone on far too long, and it’s time for her full and unconditional release.

“Nazanin Zaghari-Ratcliffe is a prisoner of conscience who should never have been jailed in the first place. She should be freed once and for all and allowed to travel back to the UK to be with her young daughter Gabriella.”

Richard Ratcliffe is also currently in New York at the UN. He is lobbying the UN and Iranian officials including President Rouhani to release his wife.