U.S. Ambassador to Libya Christopher Stevens and three of his staff members died after insurgents attacked the U.S. consulate in Benghazi on Sept. 11. The White House described the incident as an act of terror.
Republicans in the U.S. House of Representatives suggested whistleblowers in the U.S. government had highlighted security challenges in Benghazi ahead of the attack.
News website The Daily Beast reports the consulate was the target of attacks twice in the months leading up to the September assault.
U.S. Rep. Jason Chaffetz, R-Colo., told The Daily Beast that U.S. government employees had expressed concern about the security situation ahead of the attack.
"This was not a safe country on its way to a normalized situation," he was quoted as saying. "It was a very volatile situation."
The International Committee of the Red Cross had pulled out of Benghazi early this year after its staffers were attacked. The U.S. State Department issued a travel warning for Libya in August.
U.S. Secretary of State Hillary Clinton said the FBI was investigating the attack that killed Stevens.