WASHINGTON (CNN) -- A commission that investigated last year's terror attack on the U.S. diplomatic compound in Benghazi, Libya, that killed four people lacked sufficient independence and did not hold senior officials accountable, a congressional report said on Monday.
The House Oversight Committee conclusion also raised new questions about the relatively short time frame taken by the Accountability Review Board to investigate the attack by armed militants and issue its findings.
"The ARB operated under significant time pressure, completing its work and issuing a final report in just over two months," the report found.
"For some, including (the State Department), this report represented the final word on the internal failures that contributed to the tragedy in Benghazi. For others, however, the report overvalued certain facts, overlooked others, and failed to address systemic issues that have long plagued the State Department," it said.
The independent review board was launched by then-Secretary of State Hillary Clinton and criticized the department for failing to provide adequate security. It singled out mid-level officials.
But the new congressional report said the review board downplayed the importance of decision making at senior levels of the State Department.
It also criticized the conclusion that pinned accountability for security issues on certain State Department officials "based on factors that had little or no connection to the security posture" at U.S. diplomatic facilities throughout Libya.
"The haphazard decision to place the four officials cited by the (review board) on paid administrative leave created the appearance that former Secretary Hillary Clinton's decision to announce action against the individuals named in the (review board) report was more of a public relations strategy than a measured response to a tragedy," the committee's assessment said.
Secretary of State John Kerry re-instated those employees, who were reassigned to other jobs.
The new report also questioned why Under Secretary of State Patrick Kennedy, who still oversees diplomatic security at the State Department, was never disciplined or assigned responsibility.
Moreover, the report is the closest congressional investigators have come to tying Clinton to aspects of planning for the Benghazi mission before the attack.
The report said e-mails showed it is "likely Secretary Clinton's views played some role in the decision making" on the future of the mission while discussions within the State Department on the uncertain security picture in Libya were ongoing.
In response, the State Department accused the report of "twisting the facts" in an effort to advance a political agenda.
"The idea that facts are being hidden and people shielded from questioning is wrong on its face," State Department spokesman Douglas Frantz said in a statement.
"State Department officials, including former Secretary of State Hillary Rodham Clinton, have appeared at nine congressional hearings and the Department has provided thousands of pages of material to members of Congress and their staffs," he added.
Republicans have stridently criticized the Obama administration's handling of the attack as well as security preparations in eastern Libya. Some have alleged a cover-up.
Democrats on the panel have said the committee's Republican leadership has over-politicized the Benghazi matter after a thorough investigation.
Two accountability review Board members, former Ambassador Thomas Pickering and former Joint Chiefs Chairman Adm. Michael Mullen, are scheduled to testify before the Oversight panel later this week.
Kennedy is scheduled to testify before a separate hearing this week before the House Foreign Affairs Committee.