The Foreign Office is warning dual Britain-Iranian nationals against all travel to Iran, saying they face an “unacceptably higher risk” of detention and mistreatment.
In a statement, Foreign Secretary Jeremy Hunt also urged Iranian nationals living in the UK to exercise “caution” when returning to Iran to visit family or friends.
The move comes amid heightened tensions between Tehran and the West – with the United States deploying an aircraft carrier group.
It follows the reported sentencing earlier this week of Aras Amiri, an Iranian national working for the British Council in London, to 10 years imprisonment on spying charges.
She was detained in March last year when she returned to Iran to visit her elderly grandmother.
The British Council has said it firmly rejects the allegations against her.
In a statement, Mr Hunt said: “Dual nationals face an intolerable risk of mistreatment if they visit Iran.
“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 travelling to Iran.
“The dangers they face include arbitrary detention and lack of access to basic legal rights, as we have seen in the case of Nazanin Zaghari-Ratcliffe, who has been separated from her family since 2016.
“Regrettably, I must also offer a message of caution to Iranian nationals resident in the UK, but who return to visit family and friends, especially where the Iranian government may perceive them to have personal links to UK institutions or the British government.”
Mr Hunt said on Thursday he shared the US assessment of the threat as officials confirmed the security of British personnel in Iraq was being kept under constant review.
His comments followed a public clash between the Ministry of Defence and the Pentagon after the senior British officer with the coalition said there was no increased threat from Iranian proxies.
Meanwhile, Donald Trump has sought to play down fears that the two sides could be sliding towards war, after national security adviser John Bolton earlier month dramatically ordered the dispatch of the USS Abraham Lincoln carrier strike group to the region.
The president reiterated his desire for dialogue, tweeting: “I’m sure that Iran will want to talk soon.”
