"The Foreign and Commonwealth Office now advises against all travel to Iran by British-Iranian dual nationals. Travel advice has been changed in response to the Iranian government's continued arbitrary detention and mistreatment of dual nationals, and Iranian citizens with links to institutions based in the UK," the travel advice said.
The Foreign Office stressed that the Iranian security forces "may be suspicious of people with British connections, including those with links to institutions based in the UK, or which receive public funds from, or have perceived links to, the British government."
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"Dual nationals face an intolerable risk of mistreatment if they visit 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," Foreign Secretary Jeremy Hunt said, as quoted in his office's statement.
Iran does not recognise dual nationality, which "extremely" limits the UK's capacity to provide consular support to a dual national in case of their detention, according to the statement.