The Associated Press
Lawyer Abdolsamad Khorramshi says his client is being held in Evin prison and will in all likelihood stand trial soon.
The lawyer on Saturday identified his client as Hossein Rassam, the embassy's chief political analyst, and said he had not yet been able to meet with him or see the text of the indictment.
In June, Iran arrested nine local members of the British embassy staff, saying they were involved in post-election unrest.
Iranian news agencies said all but one had since been released.