Leadership and management deficiencies within the State Department were blamed for the inadequate security measures at the U.S. diplomatic mission in Benghazi, Libya, which came under attack on Sept. 11, leading to the deaths of the U.S. Ambassador to Libya, Chris Stevens, and three other Americans.

An official inquiry report released Tuesday cited "leadership and management" deficiencies within two bureaus of the State Department, poor coordination among officials and "real confusion" in Washington and in the field over the chain of command in making decisions that involved policy and security concerns, Reuters reported.

"Systemic failures and leadership and management deficiencies at senior levels within two bureaus of the State Department ... resulted in a special mission security posture that was inadequate for Benghazi and grossly inadequate to deal with the attack that took place," the unclassified version of the report by the official Accountability Review Board stated.

The two most senior members of the independent panel -- retired Ambassador Thomas Pickering and a former Joint Chiefs of Staff chairman, Adm. Mike Mullen -- will testify behind closed doors Wednesday before the House and Senate foreign affairs committees on the classified findings of the scathing report.

However, the board did not hold any State Department official responsible for the security lapses or recommend any disciplinary action. But it added that poor performance by senior managers should be grounds for disciplinary recommendations in the future, the Associated Press reported.

The panel said intelligence agencies failed to provide "specific tactical warning" of the attack and that there was "little understanding of militias in Benghazi and the threat they posed to the U.S. interests" in the eastern Libyan city.

The five-member board also found that budget restrictions in the past had led to State Department management officials rejecting several requests from the Benghazi Consulate and the embassy in Tripoli for better protection.

The report said the Consulate’s reliance on the poorly trained Libyan security guards hired by security contractor Blue Mountain Group was “misplaced.”

It also raised the possibility that the Blue Mountain guards, who were members of February 17 Martyrs' Brigade militia, left the "pedestrian gate open after initially seeing the attackers and fleeing the vicinity. They had left the gate unlatched before."

The New York Times in a report in October said that the State Department had not included Libya on a list of “dangerous postings that are high priority for extra security resources.” Currently, only the U.S. embassies in Iraq, Afghanistan and Pakistan are exempted from awarding the security contract to the lowest bidder.

Wednesday's classified testimony is expected to be followed by open hearings the next day with Deputy Secretary of State William Burns, who is in charge of policy, and Deputy Secretary of State Thomas Nides, who is in charge of management, the report said.

Secretary of State Hillary Rodham Clinton, who was slated to attend Thursday's hearing, has cancelled and is recovering from a stomach virus attack, and is under doctors' orders to rest.

In a letter accompanying the review, Clinton said she would adopt all of its recommendations.