Hardliners in Iran will present Britain’s decision to give diplomatic protection to Nazanin Zaghari-Ratcliffe, the UK citizen jailed in Iran, as an attempt by the west to interfere in internal affairs, according to a number of the country’s officials.

The announcement of the move by the foreign secretary, Jeremy Hunt, had come as the US called on the United Nations to impose sanctions on Iran for carrying out missile testing, and Donald Trump’s lawyer, Rudy Giuliani, was due to address a rally calling for regime change in Tehran.

It also came as a Ebrahim Raisi, a hardline cleric and former presidential candidate, who has been accused of extensive human rights abuses, was appointed the head of the Iranian judiciary in a blow for reformers in the country.

According to sources in Tehran, including those close to the government of Hassan Rouhani, who won the last election on a reformist agenda defeating Mr Raisi at the polls, the British government’s action will be exploited by conservatives in the judiciary, clergy and the security apparatus.

They also pointed out that the use of diplomatic protection has insidious colonial connotations in Iran. The only other time it has been evoked by the British government was during a bitter dispute over the nationalisation of the Anglo-Iranian Oil Company by Iran in the 1950s in a chain of events which ended with the overthrow of a progressive democratically elected government by Britain and the US.

Revolution in Iran: In pictures Show all 11 1 /11 Revolution in Iran: In pictures Revolution in Iran: In pictures A demonstration against the Shah in 1979 Getty Revolution in Iran: In pictures Armed women on guard in one of the main squares in Tehran at the beginning of the Iranian Revolution Getty Revolution in Iran: In pictures Demonstrators hold a poster of Ayatollah Ruhollah Khomeini, in January 1979, in Tehran, during a demonstration against the Shah AFP/Getty Revolution in Iran: In pictures Iranian rebels pose with a U.S. flag they bayonetted upside down on trees at Sultanabad Garrison northeast of Tehran on February 12 2019 AP Revolution in Iran: In pictures A gun battle in Khorramshahr during the revolution, 1979 Getty Revolution in Iran: In pictures Ayatollah Khomeini's supporters demonstrate in the streets of Tehran against the Shah among tear gas. The "black friday" caused the death of 200 people according to the Iranian government, 2000 according to the opposition, September 8 1978 AFP/Getty Revolution in Iran: In pictures Women wearing the traditional Chador demonstrate in the streets of Tehran against the Shah on September 7 1978 AFP/Getty Revolution in Iran: In pictures Demonstrators in Tehran calling for the replacement of the Shah of Iran during the Iranian Revolution, 1979. They carry placards depicting Ayatollah Mahmoud Talaghani, one of the leading revolutionaries Getty Revolution in Iran: In pictures Ayatollah Khomeini's supporters demonstrate in the streets of Tehran against the Shah. The "black friday" caused the death of 200 people according to the Iranian government, 2000 according to the opposition, September 8 1978 AFP/Getty Revolution in Iran: In pictures Thousands of the Ayatollah Khomeini's supporters on the streets of Tehran calling for the religious leader's return in January 1979 Getty Revolution in Iran: In pictures The Iranian Islamic Republic Army demonstrates in solidarity with people in the street during the Iranian revolution. They are carrying posters of the Ayatollah Khomeini, the Iranian religious and political leader Getty

The Foreign Office has stated that Mr Hunt’s declaration of diplomatic protection was the first time it had occurred in “recent memory” but has not provided details of its previous use.

The official response, so far, from the Iranian government has been from the country’s ambassador to the UK, Hamid Baeidinejad, who said in a tweet that the British move “contravenes int’l law”, adding that “Govts may only exercise such protection for own nationals.

“As UK Govt is acutely aware, Iran does not recognize dual nationality. Irrespective of UK residency, Ms Zaghari thus remains Iranian.”

The ambassador, who is not regarded as a hardliner, was restating the Iranian government’s position on dual nationality and his message is being seen by diplomats as measured and non-aggressive.

But there are rising internal tensions in Iran. Donald Trump’s jettisoning of Iran’s nuclear agreement with international powers, and re-imposition of sanctions, has led to severe economic problems in the country, strengthening the hands of the conservatives who have long opposed the deal.

The divisions led to the temporary resignation of the foreign minister, Mohammad Javad Zarif, who was the chief architect of the deal from the Iranian side. He has since stayed in his post for the time being, after President Rouhani refused to accept his resignation.

British officials have privately stressed that there had been no liaison with the Rouhani government before the announcement of diplomatic protection. The decision was taken, Mr Hunt said, to demonstrate “to the whole world that Nazanin is innocent and the UK will not stand by when one of its citizens is treated so unjustly”.

Diplomatic protection raises Ms Zaghari-Ratcliffe’s situation from a consular to a state-to-state issue and also opens the door for legal action, with the possibility of compensation if it is proved that she has been mistreated.

Any case would be dealt with by the International Court of Justice in The Hague. But senior British officials wanted to stress that there is no desire to go down the legal route for the time being.

“We are puzzled as to why this is being done, at this time. The UK knows that there are people in Iran in responsible positions who have been trying hard to resolve this matter. Jeremy Hunt has said this himself to a lot of people, we know,” said an adviser to the Rouhani government.

Iranian statesman Mohammed Mossadeq, pictured in 1951 (Getty) (Getty Images)

“It is difficult to know what this will achieve in trying to get her released. But we know that some people (hardliners) are saying this is an attempt at outside interference which must be resisted. The tactic the British are using has bad colonial meaning, especially in Iran – this is unfortunate.”

Diplomatic protection was exercised by Britain for employees of the Anglo-Iranian Oil Company after it became the Anglo-Persian Oil Company – which later became British Petroleum and then BP – and was nationalised by the Iranian government of Mohammed Mossadeq. The government in London took the measure after failing in a case disputing the nationalisation at the International Court in The Hague.

Mr Mossadeq, democratically elected, was subsequently overthrown by a coup organised by MI6 and the CIA, codenamed Operation Ajax. Many of his supporters were tortured and his closest associate, the foreign minister Hossein Fatemi, was executed by a military court of the shah of Iran whose position had been strengthened by London and Washington.

In December 1953, Mr Mossadeq was sentenced to three years solitary confinement by a military court, which rejected the death sentence sought by prosecutors, supposedly at the instigation of the shah and his western advisers. The former prime minister was, however, kept under house arrest until his death in 1967.