Nazanin Zaghari-Ratcliffe, a dual British-Iranian citizen, is in prison in Iran. Security forces have confiscated her UK passport PA

The families of Britons killed or imprisoned abroad have accused the Foreign and Commonwealth Office of abandoning its own citizens and compared the process of dealing with British diplomats as “screaming into a vacuum”.

Richard Ratcliffe, an accountant from London whose wife has been imprisoned in one of Iran’s most notorious jails since April, fears that Nazanin Zaghari-Ratcliffe, who will be 38 next week, may feel suicidal in detention.

The aid worker, a dual British-Iranian citizen, is being pressured to give up access to her two-year-old daughter, Gabriella, who is trapped in Iran after her UK passport was confiscated by the security forces.

Ms Zaghari-Ratcliffe has been placed in solitary confinement. Mr Ratcliffe, who has not seen his wife since April, told The Times last…