The Iranian ambassador to the UK has told the husband of Nazanin Zaghari-Ratcliffe that his campaign to secure her release from a Tehran jail is reducing her chances of freedom.

Speaking in response to the announcement by the Free Nazanin campaign that Zaghari-Ratcliffe had brought her three-day hunger strike to an end after prison authorities agreed she could receive medical treatment for a lump in her breast, the Iranian ambassador, Hamid Baeidinejad, claimed that she had already been given full access to the required facilities.

While the foreign secretary, Jeremy Hunt, has described the campaign by Zaghari-Ratcliffe’s husband – Richard Ratcliffe – as inspirational, Baeidinejad claimed: “The way he has tried to campaign and make this a public issue is not helpful.” He suggested that doing so was merely agitating Ratcliffe’s wife and causing her psychological distress.

The ambassador insisted that his remarks should not be construed as a threat, but said: “If her husband wants to be helpful, he should calm the situation.”

In claims likely to be rejected by Zaghari-Ratcliffe’s supporters, he added: “The way he is trying to politicise the matter and publicise it is not helpful at all and puts the lady in a very stressful situation. It is only making this more complex.”

Baeidinejad also accused Ratcliffe of lying when he claimed that the Iranian Revolutionary Guards had offered his wife freedom a month ago if she agreed to act as a spy for Iran in the UK. He insisted: “We want to help her and approach this from a humanitarian point of view.”

The relatively rare briefing by the ambassador could either be taken as a sign that the Iranians are rattled by the high-profile campaign being mounted by the Zaghari-Ratcliffes, or a genuine attempt to persuade Richard Ratcliffe to lower the profile of his campaign, and so make it easier for clemency to be granted.

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

The ambassador said that any convicted prisoner subject to a jail sentence of under 10 years could be released after serving a third of their sentence on the recommendation of the prison to the prosecutor general, so long as the individual was not deemed to be a threat to society or likely to reoffend.

Zaghari-Ratcliffe was sentenced to five years in jail more than two years ago and would therefore now be eligible for release.

Referring to her chances of clemency, Baeidinejad said: “I will let you judge if the person involved is in good conduct and is helping and assisting the prison authorities.”

Baeidinejad’s intervention came as the Free Nazanin campaign said she had been allowed to call her husband to tell him of the end of her hunger strike, which she undertook along with a fellow prisoner.

A statement said on Wednesday: “The Free Nazanin campaign can confirm with relief that Nazanin and Narges [Narges Mohammadi, an Iranian human rights activist in jail in the country] have ended their hunger strike today, and have not extended it beyond the original three days.”

Zaghari-Ratcliffe lost 3kg over the three days she was on hunger strike and suffered increasing dizziness and a constant headache, the campaign group said. Richard Ratcliffe said: “The past few days have been really stressful. I never thought three days could pass so long.”

Thanking Hunt for his intervention in summoning the Iranian ambassador on Monday, he added: “I am really glad this is over – I am still sorry it came to this, that Nazanin felt there was no other way. But I hope now those permissions mean that Nazanin will now get the medical attention she needs.”

Baeidinejad also urged Hunt to lower the profile of the case, saying: “Our function as diplomats is to try to resolve this is in a manner so that the UK and Iranian people would feel it has been handled with vigilance and care. We are doing our best to approach this from a humanitarian way and not linked to the nuclear issue or any other deal. It should be considered on its own merits.”

He said it was outrageous that the foreign secretary had suggested that Zaghari-Ratcliffe was being used as a diplomatic pawn as part of a wider Iranian attempt to force the British pay a 45-year-old debt arising from the Iranian purchase of Chieftain tanks.

He said: “We condemn this kind of statement as outrageous and unacceptable. She has received a verdict of the judge that she deserves to be in prison and that is the law, and this law should be applied to any Iranian.”

Richard Ratcliffe said on Wednesday: “I think that’s dangerously close to blaming the victim. The idea that a legal system defines its imprisonment based on how a family campaigns from the outside is extraordinary.

“There are a number of Iranian dual-nationals being held by Iran. There is no obvious pattern between those who are quiet and those who are noisy. We will keep Nazinin in the spotlight, and I told the Revolutionary Guards that before we went public.”