The officials say the bureau is not going to put agents in harm's way and that the city of Benghazi must be made secure before the FBI sends investigators there.
The officials demanded anonymity because of they are not authorized to speak on the record about an ongoing investigation.
An FBI team arrived in Libya last week to investigate the Sept. 11 deaths of Ambassador Chris Stevens and three other Americans.
Separately, the State Department is further reducing the U.S. Embassy staff in Tripoli for security reasons.
The embassy warned Americans of possible demonstrations in the capital and Benghazi on Friday.
(Copyright 2012 by The Associated Press. All Rights Reserved.)