US lawmakers were on Tuesday expected to begin scouring a top secret report which could highlight security failings surrounding a deadly attack on a US mission in Libya. The classified findings of a State Department investigation into the September 11 militant assault on the US consulate in Benghazi were Tuesday being sent to members of two House and Senate committees, a top official said. The report\'s unclassified section will be publicly available by Wednesday morning at the latest, added State Department spokeswoman Victoria Nuland. The attack in which the ambassador, Chris Stevens, and three other Americans died, has become fiercely politicized, with Republicans alleging security failings, as well as a possible cover-up over Al-Qaeda\'s role. It is likely Republicans will seek to use the report\'s findings to skewer the administration of President Barack Obama. The chairman of the Accountability Review Board (ARB), diplomat Thomas Pickering, and team member Admiral Mike Mullen, the former chairman of the Joint Chiefs of Staff, will brief lawmakers on Wednesday behind closed doors. \"The classified version of the ARB report is going to go up to the Hill later this afternoon so that members and staff of relevant committees will have a chance to look at it in advance of the classified briefings,\" Nuland said. It will be accompanied by a letter from US Secretary of State Hillary Clinton, who had been due to testify to Congress this week, but has been told to rest at home by doctors after suffering a stomach bug and a concussion. Nuland categorically denied suggestions from some observers that Clinton may be faking her illness in a bid to avoid testifying on the Benghazi inquiry. Such claims were \"completely untrue,\" Nuland said. \"We\'ve been very clear from the beginning that she had a stomach virus, an ugly stomach virus. She got very dehydrated. She fainted. It was later discovered she had sustained a concussion.\" She accused critics of \"wild speculations based on no information,\" adding Clinton was working from home and was in email and phone contact with staff. The Benghazi report was sent by courier to Clinton at home on Monday, and she has read the highly-anticipated findings. But Nuland refused to give any further details, until the unclassified part of the report has been made public.