Anoosheh Ashoori has said he will not be able to celebrate his return to the UK until the release of other detainees in Iran.

Mr Ashoori, 68, a retired civil engineer, was arrested in August 2017 while visiting his elderly mother in Tehran, and held in Evin prison – a place he called the “valley of hell”.

Despite living in the UK for 20 years, Mr Ashoori was convicted of spying for Israel’s Mossad intelligence agency and sentenced to 10 years in prison.

He arrived back in the UK last week on the same flight as Nazanin Zaghari-Ratcliffe, another British-Iranian who spent six years in detention in Iran.

Mr Ashoori said he “100%” agreed with what Mrs Zaghari-Ratcliffe had said during a press conference about how she should have been released six years ago.

Speaking on Sky News’ Beth Rigby Interviews, Mr Ashoori said: “I agree with Nazanin 100%. She in fact put her finger on the right button by saying that.

“She should have been here years ago if that debt was paid. That wasn’t a ransom that was a debt that the British government owed.

“It should have been paid and if it was paid perhaps none of this would have happened. So yes, I feel a bit angry.”

Mrs Zaghari-Ratcliffe said it had taken too long for the Government to pay a £400 million debt to Iran, which helped secure her release.

Speaking about other people still detained in Iran, including wildlife conservationist Morad Tahbaz, a British-US national, Mr Ashoori said: “Such fine people. Such nice people. Morad Tahbaz, he should be here with us.

“He needs medical attention, and he is not getting it. We cannot celebrate anything without them being here.

“I am feeling so bitter that he was not on the same plane with us and I’m not going to be quiet until he is back and until the rest of the dual nationals are released.

“I feel I have left such fine people.”

Mr Ashoori, who said he attempted suicide and went on hunger strike while in prison, said the focus should not be on the people who have been released, but on those who are still detained.

“I think the best thing for us is that we should concentrate not on us, because we are now safe, we are here.

“We should concentrate on the people we have left behind,” he said.

The husband and father said many of them are innocent and their lives have been destroyed.

He told Sky News: “I cannot be joyful because I’ve got friends back there who are going through the same suffering.

“How can I celebrate? How can I be happy?”

Mr Ashoori added: “Again I stress on the fact that Morad is one of them but there are many others.

“But I’m not at liberty to name them. They are there. And the feeling, the suffering is more intensified when you are left behind.”

Mr Ashoori said that he had dreams about his wife Sherry and his children while he was in prison.

He said Sherry is his “best friend in life”, adding: “Even now, I was touching Sherry’s hand to make sure this is reality this is happening.

“We became serious when she was 17, we were boyfriend and girlfriend, and we are still boyfriend and girlfriend.”

Asked how he will celebrate his birthday next month, he said: “I’ll leave it to Sherry and the kids, but again it is not going to be a full celebration.

“Unfortunately the main celebration is when Morad returns together with the rest of the dual nationals then we are going to raise our glasses of champagne altogether.”

– Beth Rigby Interviews… is on Sky News at 9pm on Thursday. Also available on the Sky News YouTube channel.