WASHINGTON (MarketWatch) -- Contractors hired by the U.S. Defense and State departments to help support operations in Afghanistan and Iraq have wasted or stolen billions of tax payer dollars since 2002, according to a Congressional report released this week. Of the $206 billion the Pentagon has spent, at least $31 billion, and possibly as much as $60 billion, have been lost, according to the House Commission on Wartime Contracting. Meanwhile, the DoD auditing agency tasked with auditing all contractors is falling behind with a backlog of $600 billion in unaudited work, which could exceed $1 trillion by 2016. The report comes as the State Department plans to increase its manpower in Iraq by 8,000 to 17,000, , as the U.S. military gradually pulls out, primarily by hiring contractors.