Richard Ratcliffe has gone on hunger strike over the government’s “inaction and failure” in its handling of his wife's case.

West Hampstead's Nazanin Zaghari-Ratcliffe has been in custody in Iran since 2016 – when she was visiting family with her daughter – after being accused of plotting to overthrow the government. In April she was given a further sentence of a year.

Husband Richard is beginning a hunger strike outside the Foreign Office and intends to sleep in a tent after his wife lost her latest appeal in Iran.

On a petition on Change.Org, Mr Ratcliffe wrote on Sunday (October 24): "We are beginning a hunger strike today. This time by the Foreign Office and Downing St. It comes in response to Nazanin’s latest conviction. Her lawyer was informed by phone her appeal was rejected, without the inconvenience of a court hearing."

He wrote that he asked foreign secretary Liz Truss what the government’s response would be.

"The answer was nothing yet," he said.

Nazanin's imprisonment has been linked with the UK’s failure to pay an outstanding £400 million debt to Iran for tanks that were not delivered after the overthrow of the Shah in the late 1970s.

Richard wrote: "They still do not settle the debt to Iran whose impasse in 2016 caused Nazanin to be taken. There is no legal impediment now, the minister said.

"But also they do nothing to disincentivise Iran’s hostage taking, still refuse to use the word ‘hostage’ despite promises to Nazanin. They still seem surprised each time Iran escalates – but it still happens cost free. They still say the same slogans. At some point, soundbites don’t protect you."

He wrote that "the government has linked Nazanin’s fate to the revival of the JCPOA, and improved US-Iran relations" and said that "as these stalled, so have we".

"It can be difficult to capture the feeling of a life wasting away, watching prison creep closer while we sit in the PM’s in-tray. Nazanin was increasingly distraught last week," he wrote.

"Two years ago I went on hunger strike in front of the Iranian Embassy, on the eve of Boris Johnson taking over as prime minister. Two years ago we were allowed to camp in front of Iranian embassy for 15 days – much to their considerable anger. But it got Gabriella home.

"We are now giving the UK government the same treatment. In truth, I never expected to have to do a hunger strike twice."

He wrote that Iran remains the "primary abuser" but that the family is "caught in a dispute between two states".

"The UK is also letting us down. It is increasingly clear that Nazanin’s case could have been solved many months ago – but for other diplomatic agendas. The PM needs to take responsibility for that. Who does the government answer to for the choices it makes? Who takes responsibility?"

He calls on the government to recognise Nazanin and others detained in Iran as hostages; impose sanctions or take Iran to court; keep "the PM’s promise from 2017 to settle the debt"; and commit to "pushing for an end to hostage-taking an explicit part of the JCPOA nuclear negotiations and a condition for the revived nuclear deal".

He asked supporters to sign the petition and to encourage MPs to visit and sign the visitors book.

A patchwork blanket will be created during the strike, with people asked to decorate a patch and send it to Amnesty UK.

A spokeswoman for the Foreign, Commonwealth and Development Office (FCDO) said: “Iran’s decision to proceed with these baseless charges against Nazanin Zaghari-Ratcliffe is an appalling continuation of the cruel ordeal she is going through.

“Instead of threatening to return Nazanin to prison Iran must release her permanently so she can return home.

“We are doing all we can to help Nazanin get home to her young daughter and family and we will continue to press Iran on this point.”