Husband's plea for British-Iranian Nazanin Zaghari-Ratcliffe

A British man has described the imprisonment of his wife by Iran's Revolutionary Guard as "outrageous and arbitrary".

Charity worker Nazanin Zaghari-Ratcliffe, 37, was arrested on 3 April at an airport after visiting her family.

An online petition set up to urge Prime Minister David Cameron to step in has attracted more than 3,000 signatories.

Nazanin's husband Richard spoke to the BBC's Daniel Boettcher.