Because of failures within the US State Department, security at the US mission in Benghazi, Libya, was grossly inadequate to deal with the Sept 11 attack that killed the US ambassador and three others, an official inquiry found on Tuesday.

In a scathing assessment, the review cited "leadership and management" deficiencies at two department offices, poor coordination among officials, and "real confusion" in Washington and in the field over who had the responsibility, and the power, to make decisions that involved policy and security concerns.

The attack killed Ambassador Christopher Stevens and three other US citizens, and set off a political furor as Republicans harshly criticized Democratic President Barack Obama over the incident before the Nov 6 election in which Obama won a second term in office.

The report's harsh assessment seemed likely to tarnish the four-year tenure of Secretary of State Hillary Clinton.

"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," said the unclassified version of the report by the official Accountability Review Board.

The board specifically faulted the department's Bureau of Near Eastern Affairs, the regional office that is responsible for the Middle East and North Africa, and the Bureau of Diplomatic Security, its law enforcement and security arm.

The five-member board said US intelligence provided no "specific tactical warning" of the attack and that there was "little understanding of militias in Benghazi and the threat they posed to US interests" in the eastern Libyan city, where the central government has little influence.

The incident has raised questions about the adequacy of security at US embassies around the globe and where to draw the line between protecting US diplomats in dangerous places while giving them enough freedom to do their jobs.

Jon Alterman, head of the Middle East program at the Center for Strategic and International Studies, said the assessment reflected poorly on Clinton, and its recommendations will probably make life harder for diplomats in the field.

"This is a mark against Secretary Clinton. While she was not singled out, the report highlighted the lack of leadership and organization on security issues, and those fall into her bailiwick," Alterman said.

"The report, however, relies a little too much on bureaucratic fixes," he added. "Sprinkling people throughout the system who are not only empowered to say 'no,' but have an institutional interest in doing so, will make it harder for diplomats to get out of tightly guarded facilities."

Despite those failures, the Accountability Review Board determined that no individual officials ignored or violated their duties and recommended no disciplinary action now. But it also said poor performance by senior managers should be grounds for disciplinary recommendations in the future.

Reuters-AP