The husband of a British-Iranian woman being held in an Iranian jail said the case had now gone beyond his worst fears, with the two-year anniversary of her detention due to pass on Tuesday without any sign of her release.

The MP Tulip Siddiq said she believed Richard Ratcliffe, the husband of Nazanin Zaghari-Ratcliffe, had been given false hope by the Foreign Office in the run-up to Boris Johnson’s visit to Iran late last year.

She said she had seen hope ebb away after the charity worker was detained past Christmas and also beyond the Iranian new year two weeks ago.

Ratcliffe has not seen his wife or his daughter Gabriella since his wife’s detention in 2016.

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

A comedy night on Tuesday – the second anniversary of her detention – was originally planned as a celebration of her release, which Ratcliffe had been expecting before Christmas.

“I was pretty hopeful at Christmas, but then I thought worst-case scenario it would be Nowruz – Iranian new year – which was two weeks ago,” he told the Guardian. “So in my head, worst case was that she would be out by March, so now the fact is we’ve got to the second anniversary. We have a comedy event tomorrow which we had originally planned as a celebration. Now, we need cheering up.

“We’ve done a lot of campaigning, and now it feels like a standoff. And the wider mood music between Iran and the UK is taking a turn for the worse at the moment.”

Ratcliffe and Siddiq have previously criticised the foreign secretary for incorrectly claiming that Zaghari-Ratcliffe was training journalists in Iran, for which he apologised.

Johnson met the pair before his visit to Iran and pledged to fight for Zaghari-Ratcliffe’s release, Siddiq said, but now the MP said she was being stonewalled by the Foreign Office.

Siddiq said she would push for a meeting between Ratcliffe and Theresa May. “Boris Johnson has been to Iran and there have been no results. It’s been two years and I feel like the only way to get her out now is to escalate this even further,” she said.

“I feel so desperate as a local MP, because I really thought we would get her home by Christmas. I feel Richard was given false hope, especially after the foreign secretary made that grave error in front of the select committee, it felt like it was the most important issue for the Foreign Office once we sat down with Boris Johnson, he said no stone will be left unturned.”

Ratcliffe and his supporters have asked prominent comedians and MPs to send jokes they will compile into a calendar for Zaghari-Ratcliffe to keep her spirits up in prison. The jokes will also be hung as decorations on a tree in their local park in north-west London, where they marked the first anniversary of her detention last year.

Ratcliffe said they had made several applications for his wife to be given temporary leave from prison. Such a move would let her be with her three-year-old daughter, who has been cared for by her grandparents since her mother was detained.

Ratcliffe said he had felt drained by the campaigning. “We felt there were clearly lots of signs for hope and it just didn’t happen,” he said. “The head of the prison said he’d approved her release many months ago. Then we thought she might get furlough – a holiday from prison at her mum and dad’s house – then that transformed to house arrest with Gabriella, with guards outside, which sounded just awful.”

Ratcliffe said his wife had been told by a judge the only reason she remained in prison was because of a long-running dispute over a cancelled arms deal that predates the Iranian revolution.

Both the Iranian embassy and the Foreign Office have denied her detention is linked to the £450m debt, which Britain has accepted that it is liable for, but disagreements remain over the interest and how the money could be returned without breaking international sanctions.

Iran’s pre-revolution government ordered 1,750 UK-built tanks, most of which were never delivered after the revolution in 1979.

Ratcliffe said it felt like there was a standoff at government level. “[Nazanin] is not being held because of something she has done, she is being held because of something the government hasn’t done,” he said.

A Foreign Office spokeswoman said: “On the second anniversary of Nazanin’s arrest we continue to approach her case, and all of our British-Iranian consular cases, in a way that we judge is most likely to secure the outcome we all want. Therefore we will not be providing a running commentary on every twist and turn.”