Iran has released a British embassy staffer, leaving one of the embassy's local staff in jail, the Foreign Office in London said Monday. British Foreign Secretary David Miliband has called the detentions "unacceptable and unjustifiable." "We are confirming that one of our staff remains in detention," a Foreign Office representative told CNN, declining to be named, in line with British government policy. "It remains our top priority to get all our staff freed."