WASHINGTON — An independent investigation into the deadly Sept. 11 attack on the U.S. diplomatic mission in Benghazi, Libya, is complete, and Congress will be briefed on its findings this week, the State Department said Monday.

The classified report by the Accountability Review Board will be sent to Capitol Hill on Tuesday, a day before the panel’s two most senior members will testify in closed session before the House and Senate foreign affairs committees. The board was established to examine the attack that killed U.S. Ambassador to Libya Chris Stevens and three other Americans.

An unclassified version of the report is expected to be released to the public after board Chairman Thomas Pickering, a former ambassador, and Adm. Mike Mullen, a former chairman of the Joint Chiefs of Staff, appear at Wednesday’s hearings, said State Department spokeswoman Victoria Nuland.

The House Foreign Affairs and Senate Foreign Relations committees will then hear open testimony on the report on Thursday from William Burns and Thomas Nides, Secretary of State Hillary Clinton’s two main deputies, Nuland said.

Clinton created the board in the aftermath of the Benghazi attack to look into security procedures before and during the incident in which heavily armed militants laid siege to the mission and a nearby CIA annex. She had been scheduled to appear before the committees this week, but canceled after fainting and sustaining a concussion while recovering from a stomach virus that left her severely dehydrated.

Nuland said Clinton had been given a copy of the report on Monday.

She added that Clinton was “on the mend” but was obeying her doctors’ recommendations to stay at home this week.