"Mrs Zaghari is an Iranian. She has been convicted on security charges and is spending her sentence in prison," Iranian Foreign Ministry Spokesman, Abbas Mousavi, was quoted as saying by the state media.
"Iran does not recognize dual nationality," he said.
Foreign Office minister Andrew Murrison pressed Iran for the "urgent and unconditional release" of Zaghari-Ratcliffe on Sunday, during a visit to Iran to discuss the situation in the Middle East, his ministerial area of responsibility.
Fears of a direct military confrontation between Washington and Tehran have risen sharply since Iran shot down a U.S. drone last week and U.S. President Donald Trump called off a retaliatory strike while bombers were in the air.
Zaghari-Ratcliffe, a project manager with the Thomson Reuters Foundation, was arrested in April 2016 at a Tehran airport as she headed back to Britain with her daughter after a family visit.
She was sentenced after being convicted of plotting to overthrow Iran's clerical establishment, a charge denied by her family and the Foundation, a charity organization that operates independently of Thomson Reuters and Reuters News.
Zaghari-Ratcliffe's husband Richard started a hunger strike outside the Iranian Embassy in London last week to draw attention to his wife's plight.
"We do not approve such measures.. They are against international conventions," Mousavi said in the statement. "If someone has a request, we advise them follow it through legal channels and let the Iranian embassy do its work."
In an email to Reuters Ratcliffe said his wife still faced a second court case and was being prevented from seeing their daughter Gabriella."I saw Minister Araqchi also accused me of blackmailing Iran by my hunger strike. Which is ironic since I am not the one who is holding an innocent person as diplomatic leverage," he said.Zaghari Ratcliffe, was reportedly on a hunger strike as well from prison, in unison with her husband, demanding her unconditional release last week - sparking her husband's decision to hold such protests.This is one of many hunger strikes the dual-national prisoner has undergone since her initial arrest. This strike, however, comes amid growing tensions between Iran and the international arena, as Tehran has been widely condemned for the attacks on two oil tankers in the Gulf of Oman this week.Foreign Secretary Jeremy Hunt pleaded with Iran to "do the right thing... Our message to Iran is whatever the disagreements you may have with the United Kingdom, there is an innocent woman at the heart of this," according to the BBC.Zaghari-Ratcliffe proclaimed to Iranian authorities that she would begin her hunger strike, while still drinking water, to fight her "unfair imprisonment." Her husband also plans to stand in solidarity with her, as he has begun his own hunger strike to "keep her story public," urging the next UK prime minister to make it top priority to "protect British citizens from unfair imprisonment, from torture."Hunt granted Zaghari Ratcliffe diplomatic protection in March, but Tehran refused the call."Nazanin is a prisoner of conscience, unfairly jailed after a sham trial and subjected to all manner of torments - including months in solitary confinement and endless game-playing over whether she would receive vital medical care," said Amnesty International UK's director Kate Allen, according to the BBC.She became suicidal months after her initial arrest, following her first hunger strike, her husband told the British Guardian.Iranian authorities have held Zaghari-Ratcliffe at the Islamic republic's infamous Evin prison, for apparently spying on Iran for the British authorities. She was arrested that April at an airport in Tehran while preparing to return from a family visit in Iran back to the UK along with her young daughter, according to her family.Ratcliffe, husband of the incarcerated project manager for the London-based charity organization, said his wife was "at a breaking point" already at the time, the Guardian reported in 2016.“When [Iranian-Canadian professor] Homa Hoodfar was released [in September], she was really hopeful that she would be next and she got moved into a big room," he told the British newspaper. "She was very excited. Then she got moved back to a small room, which gave her a sense that nothing is going to happen, and that’s when she started feeling suicidal.”He said that his wife had not mentioned the hunger strike when they spoke about it in 2016, but he was later informed of it by prison authorities who summoned the family to the jail.“They received a call to go to Evin prison [at the time] for an emergency visit for the whole family. It had never happened before,” he said."She was complaining about pain in her hands, arms and neck and that she was having strange palpitations, and that she was having blurred vision – clearly the impact of her diet, her long incarceration."He added that Richard Ratcliffe's mother was distressed to see the deterioration of her daughter's condition. "When her mum saw her on [that day], her mum passed out.”Citing concerns by the chief executive of the Thomson Reuters Foundation, Monique Villa, the Guardian reported that the imprisoned aid worker had eventually been convinced by her mother to eat some cheese.The following August, British Prime Minister Theresa May raised concerns with Iran's President Hassan Rouhani over several cases involving dual British-Iranian nationals, including Zaghari-Ratcliffe."The Prime Minister raised concerns about a number of consular cases involving dual nationals, including that of Mrs Zaghari-Ratcliffe, and stressed the importance of resolving these cases as we worked to strengthen our diplomatic relationship," May's office said after the two leaders spoke on the telephone.In April of this year, Iran's Foreign Minister Mohammad Javad also said he was willing to swap British-Iranian aid worker Nazanin Zaghari-Ratcliffe, for an Iranian woman detained in Australia for the past three years on a U.S. extradition request."I feel sorry for them, and I have done my best to help," Zarif said of Zaghari-Ratcliffe. "But nobody talks about this lady in Australia who gave birth to a child in prison. ... I put this offering on the table publicly now - exchange them."Later, in an interview with Reuters, Zarif backed off from a possible prisoner swap for the two women saying the Zaghari-Ratcliffe case was a separate issue, which he was discussing with the British government."The offer that I made was people who have been in prison either in the United States or elsewhere in the world on American request," he said, "But the Iranian-British woman is a separate case."Zarif told Reuters he was proposing "a serious dialogue" with the United States on a possible prisoner swap.At the Asia Society, Zarif said Iran proposed a possible prisoner swap deal to the US administration six months prior, but had not yet had a response from Washington."All these people that are in prison inside the United States, on extradition requests from the United States, we believe their charges are phony. The United States believes the charges against these people in Iran are phony. Let's not discuss that," he said."Let's have an exchange. I'm ready to do it and I have authority to do it," Zarif said.The family of Zaghari-Ratcliffe, revealed in 2017 that she had been accused by a Revolutionary Court of acting against national security by cooperating with the BBC.Iran's judiciary spokesman said that year that Iranian appeals court confirmed the five-year jail sentence for her.Her family said in a statement that the appeal "was held in secret, in the presence of a large number of Revolutionary Guards". Neither Zaghari-Ratcliffe nor her lawyer had been allowed to tell the family what happened at her trial.However, the family said that at the appeal hearing two new accusations have been raised against her: being the head of recruitment for the BBC Persian service, and knowingly being married to a British spy.Iran's judiciary was not immediately available for comment when Reuters attempted to contact officials at the time. Reuters was also unable to independently confirm the new accusations.Speaking in response to Zaghari-Ratcliffe's jail sentence, Francesca Unsworth, director of the BBC World Service Group, said in January of 2017:"Mrs Zaghari-Ratcliffe has never worked for BBC Persian. She worked briefly for BBC Media Action, our international development charity, in a junior administrative capacity."Unsworth then called on Iranian authorities to urgently re-examine the case.Iranian authorities have accused the BBC Persian service of trying to overthrow the Islamic Republic, especially after its coverage of widespread protests in Iran over disputed election results in 2009. BBC has denied the allegations.Zaghari-Ratcliffe works for the Thomson Reuters Foundation, a London-based charity that is independent of Thomson Reuters and operates independently of Reuters News."The lack of justice in Nazanin's case continues to be a stain on Iran," Richard Ratcliffe, husband of Zaghari-Ratcliffe, said in a statement."It is a needless waste of a mother and child's life for their own political bargains and economic interests."Several Iranian dual nationals from the United States, Britain, Canada and France have been detained in the past few years and are being kept behind bars on charges including espionage and collaborating with hostile governments.Earlier in May, The Foreign and Commonwealth Office (FCO) intensified its warning to both British and British-Iranian dual nationals on traveling to Iran, advising both parties to avoid it at all costs."There is a risk that British nationals, and a higher risk that British/Iranian dual nationals, could be arbitrarily detained in Iran. All British nationals should consider carefully the risks of traveling to Iran. The Iranian authorities don’t recognize dual nationality for Iranian citizens and therefore don’t grant consular access for FCO officials to visit them in detention.The strict warning comes a few days after an Iranian British Council Member Aras Amri was reportedly sentenced to 10 years in prison for allegedly spying on Iran for the British government. She herself was arbitrarily detained in Iran earlier in 2018 while on a family visit."Dual nationals face an intolerable risk of mistreatment if they visit Iran," Foreign Secretary Jeremy Hunt said in the statement.Hunt also said he needed to caution Iranian nationals living in Britain, who returned to Iran to visit family, that they might be perceived to have personal links to British government institutions.Iranian security services might be suspicious of other people with British connections, including those linked to institutions based in the UK, Britain's Foreign Ministry said."Despite the UK providing repeated opportunities to resolve this issue, the Iranian regime’s conduct has worsened. Having exhausted all other options, I must now advise all British-Iranian dual nationals against traveling to Iran."The instructions advise British citizens not to come within within 100 kilometers from the borders of Iraq, Afghanistan or Iran."If you’re a British-Iranian dual national and are subsequently detained in Iran, the FCO’s ability to provide consular support is extremely limited," read the updated advisory warning on the FCO's website.The warning came amid heightened tensions between Iran and the West, with Hunt saying on Thursday that Britain agreed with the United States that Tehran posed an increased threat.The FCO gave a similar warning last month after the heavy rainfalls which caused massive flooding and damages all around Iran, and advised against "all but essential travel" to the Islamic Republic. The FCO claims that there are possible water-born diseases which could be contracted as well as warnings about previous protests in the country, exclaiming that it is not safe for British citizens to travel to the country, for both political and health reasons.