Nazanin Zaghari-Ratcliffe, a charity worker from London, has been detained for more than three years over spying allegations she denies.

Mr Ratcliffe said escalated tensions after the killing of Qasem Soleimani could make matters worse for his wife.

He plans to meet with Prime Minister Boris Johnson to discuss her case.

"There's probably a concern, on a selfish level, as to what does this mean for Nazanin's case," he said.

"There's always a worry that things could get worse."

Mr Ratcliffe, whose in-laws live in Iran, said he is concerned about the implications for the region as a whole.

Mrs Zaghari-Ratcliffe's parole was refused shortly before Christmas, he said, noting that she was "low" when he spoke to her on Christmas Day and New Year's Day.

"We're obviously not hopeful at the moment... We were feeling like there's been no good news for a while, and I was getting ready to push the prime minister and the government to do more and to be a lot more assertive," he said.

"In some ways that still feels the right thing to do - but absolutely the wrong time."

The couple's British-born daughter Gabriella, who had been living with her grandparents in Tehran, returned to the UK in October.

Mr Ratcliffe's concern comes amid a major escalation in tensions between Washington and Tehran.

Iran's supreme leader has vowed "severe revenge" on those responsible for the death of Soleimani, who was killed by an air strike at Baghdad airport early on Friday ordered by US President Donald Trump.

The 62-year-old spearheaded Iran Middle East operations as head of the elite Quds Force. Mr Trump said Soleimani killed or wounded thousands of Americans.

US officials have said 3,000 additional troops will be sent to the Middle East as a precaution.

Mr Ratcliffe said it is "time to find a way to improve relations" between the West and Iran and to bring his wife home.

He said he received a letter from Mr Johnson shortly after the general election last month asking for a meeting, but that a date was not specified.

While he was foreign secretary, Mr Johnson mistakenly said that Mrs Zaghari-Ratcliffe had been in Iran training journalists.

"We've been quite clear in public that I feel he owes us and that he needs to do what he can to bring Nazanin home and to bring [home] the others held over similar reasons," Mr Ratcliffe said.

He added: "As we're on the precipice of very dark times, it can only help that positive gestures are made."