Iran has responded to Britain’s decision to grant Nazanin Zaghari-Ratcliffe diplomatic protection, calling it illegal.

The charity worker, who is serving a prison sentence in Tehran for “espionage”, was yesterday extended the protection - the first such time in the UK’s recent history - in a fresh attempt to secure her release.

Hamid Baeidinejad, Iran’s ambassador to the UK, tweeted in response that the Government’s exceptional decision “contravened international law”.

“Governments may only exercise such protection for own nationals,” he said. “As the UK government is acutely aware, Iran does not recognise dual nationality. Irrespective of UK residency, Ms Zaghari thus remains Iranian (sic).”

Mrs Zaghari-Ratcliffe, a dual British-Iranian national who had been living in London with her husband Richard and daughter Gabriella, was arrested during a family visit to Tehran in 2016.