Nazanin Zaghari-Ratcliffe, the British-Iranian woman held by Tehran, started a hunger strike after her interrogators tried to persuade her to become a spy, her husband has claimed.

Richard Ratcliffe revealed his wife was calm as she began an initial three-day hunger strike in protest at the Iranian prison authorities’ refusal to give her a clear written undertaking that she would receive medical help for a lump on her breast, as well as other concerns.

He was speaking as the British foreign secretary, Jeremy Hunt, summoned the Iranian ambassador to demand the dual national, sentenced to five years in prison for espionage, was given proper medical help.

Ratcliffe said it was “now or never” for Hunt to escalate the situation by saying the British government would give his wife diplomatic protection, a means by which the row would be elevated to a state-to-state dispute, making an international legal claim for her to be visited by UK authorities in prison more likely to be granted.

Later on Monday, Ratcliffe met Hunt for about 40 minutes and discussed the prospect of granting his wife diplomatic protection.

Profile Who is Nazanin Zaghari-Ratcliffe? Show Hide 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 Foreign Office spokeswoman said: “The foreign secretary discussed this course of action with Richard Ratcliffe today and will continue to actively consider the question of diplomatic protection, alongside all other options in Nazanin’s case and the cases of other dual nationals detained in Iran.”

Ratcliffe said the foreign secretary vowed to “do all we can” to return his wife. Hunt described Ratcliffe as “inspirational” in a tweet featuring a picture of their meeting. “We will not rest until she is home,” he said.

Jeremy Hunt (@Jeremy_Hunt) Good to meet Nazanin’s inspirational husband Richard Ratcliffe earlier. We will not rest until she is home. #FreeNazanin pic.twitter.com/l0dsa2VG4K

The Iranian ambassador to the UK, Hamid Baeidinejad, said Hunt’s intervention in the internal affairs of Iran would not help Zaghari-Ratcliffe, but instead increase the hostility of the Iranian people towards the UK.

Earlier, Ratcliffe had praised the foreign secretary’s tougher rhetoric, but said it was time for more action, pointing out the request to give diplomatic protection had been tabled more than a year ago.

He said the decision to disclose pressure on his wife from Iran’s Revolutionary Guards to spy via a job with British Aid was difficult, but he had been appalled by the associated warning that if she did not agree to the offer, there would be consequences for her family in Iran.

“She was told it would be safer for her and safer for her family afterwards if she agreed to do this,” he said. “She was told to think about it and that they would return. She had been terrified ever since.”

He said he had written to the Iranian foreign minister, Javad Zarif, to protest against the threat, and had informed the Foreign Office. He also released an account of the demands that she should spy for Iran, adding that everything in the country was filmed, and if she had agreed, it would have been used against her. It was the first time the Revolutionary Guards had visited her for more than a year.

Zaghari-Ratcliffe refused the offer outright, he said, insisting she did not wish to spy for either the UK or Iran.

He said the request to become a spy for Iran was made on 29 December at the same time as the Iranians offered a short-term release in January. Ratcliffe said a previous release turned out to be part of a power game in which Iran bartered her case for a favourable court outcome in the Iranian-British dispute over money owed to Iran by the UK for the sale of arms more than three decades ago.

Ratcliffe claimed his wife had been used as a clear bargaining chip in two previous hearings.

On Sunday, speaking in London at the start of his wife’s hunger strike, he also disclosed that Iranian prison authorities had discussed her condition with her for an hour and a half, but said they became angry when she demanded undertakings in writing to improve her medical help. “There have been too many broken promises and blockages to rely on empty words,” Ratcliffe said.

He added that her experience was that prison authorities played a game in which one branch of government made an offer, but only conditional on additional permission being given by another branch. The Iranians, he said, “were involved in an elaborate game of pass the responsibility”.

He said the Iranian prison medical chief had offered Zaghari-Ratcliffe a step-by-step process, as long as she complied with the Iranian prison regime, but refused to put this in writing. In recent months she had been denied medical help for a lump on her breast, pains in her neck, numbness in her legs and psychiatric difficulties.

Play Video 1:19 Iranian state TV broadcast 2016 arrest of Nazanin Zaghari-Ratcliffe – video

The demands of the hunger strike, he said, were to see a specialist medical doctor and for any remedies they proposed to be granted.

Ratcliffe described the Iranians as scrambling in response to public pressure. “This is not a game,” he said, adding that he knew if she chose to extend the hunger strike, the risks would multiply.

Monique Villa, the chief executive of the Thomson Reuters Foundation, Zaghari-Ratcliffe’s employer, said denying her employee medical access, including for new lumps found on her breasts in December, was a form of torture.

“She’s not spy material,” Villa said. “She’s innocent. She should be released immediately and she should have immediate medical access.”