THE sister-in-law of jailed British-Iranian mother Nazanin Zaghari-Ratcliffe has said it is "hard to get too excited" about the possibility of her release, having had disappointments in the past.

Rebecca Ratcliffe - who is a GP in Cwmbran - was speaking after it was reported on Tuesday that her sister-in-law – who was jailed in Iran almost six years ago – had been given one of her passports back.

And now Boris Johnson has confirmed a British negotiating team was working in Tehran to secure the release of dual nationals, while Mrs Zaghari-Ratcliffe remains at her family home in the Iranian capital.

Speaking on BBC Breakfast, Ms Ratcliffe said: “We know that there’s a delegation, a UK delegation, gone over there to talk to Iranian officials and hopefully negotiate so it seems like a very positive step in Nazanin’s case, and hopefully coming close to an end but we just don’t know how far it’s gone.”

She said the case could come to a close very quickly or could be “a stunt” on Iran’s part.

She said: “This may all be over in a week or two. But also it may just be a stunt from the Iranians.

"We’ve had this before. You know, we’ve had many ups over the last six years and been told she’s been about to be released. So there’s an element of false hopes and I think our family, Nazanin, her parents, find it hard to get too excited at the moment.”

She said developments in the case, whether good or bad “drive (Nazanin) into a state of high anxiety, adding: “So since Sunday, neither Nazanin nor her parents can settle. I think there’s a lot of twitching going on in that flat, a sort of high tension and just waiting to see what happens.”

The prime minister, speaking during a trip to the Middle East, said negotiations are “moving forward” and “going right up to the wire”. But he was cautious not to elaborate further on the state of negotiations with Tehran “because those negotiations continue to be under way”.

“I really don’t think I should say much more, I’m sorry, although things are moving forward,” he told broadcasters at the Emirates Palace hotel in Abu Dhabi.

“I shouldn’t really say much more right now just because those negotiations continue to be under way and we’re going right up to the wire.”

Mrs Zaghari-Ratcliffe was arrested in April 2016 as she prepared to fly back to the UK, having taken her daughter Gabriella – then not even two years old – to see relatives.

She was accused of plotting to overthrow the Iranian government and sentenced to five years in jail, spending four years in Tehran’s Evin Prison and one under house arrest.

Both the British Government and Mrs Zaghari-Ratcliffe have always denied the allegations.

While the details of the negotiations remain unclear, it is possible they are linked to a £400 million debt dating back to the 1970s owned to Iran by the UK.

The Government accepts it should pay the “legitimate debt” for an order of 1,500 Chieftain tanks that was not fulfilled after the shah was deposed and replace by a revolutionary regime.

Tehran remains under strict sanctions, however, which have been linked to the failure to clear the debt.