Richard Ratcliffe
They fear the 39-year-old is being used as a 'bargaining chip'.
The arrest comes after two other British-Iranians were detained in recent weeks.
April 3 marks two years since the mother-of-one's arrest.
The British-Iranian national is suffering 'exceptionally harsh treatment'.
Foreign Secretary promises to raise 'serious concern' for jailed Briton.
'Make sure you enjoy the little things in life'
Husband Richard Ratcliffe calls the development 'terrific news'
Her husband is 'waiting on tenterhooks' for news.
Iranian officials are judging whether she's fit to be in jail.