Updated

A top Iranian diplomat says the U.K.'s decision to give diplomatic protection to a British-Iranian national detained in Iran for nearly three years contravenes international law.

British officials have said Iran has failed to meet its international obligations in its treatment of Nazanin Zaghari-Ratcliffe.

The Iranian ambassador to Britain, Hamid Baeidinejad, said in a tweet Friday: "UK Govt's extension of diplomatic protection to Ms Zaghari contravenes int'l law. 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."

Zaghari-Ratcliffe was arrested in April 2016 while traveling with her toddler daughter in Iran. Her five-year prison sentence for plotting the "toppling" of its government has been widely criticized.