Washington, D.C. ? Military contracts in the Iraq theater have cost taxpayers at least $85 billion, and when it comes to providing security, they might not be any cheaper than using military personnel, according to a report released Tuesday.

The Congressional Budget Office report comes on the heels of increased scrutiny of contractors in the last year, some of whom have been investigated in connection with shooting deaths of Iraqis and the accidental electrocutions of U.S. troops.

The United States has relied more heavily on contractors in Iraq than in any other war to provide services ranging from food service to guarding diplomats. About 20 percent of funding for operations in Iraq has gone to contractors, the report said.

Currently, there are at least 190,000 contractors in Iraq and neighboring countries, a ratio of about one contractor per U.S. service member, the report says.

The study does not include monetary figures for 2008, so the total paid to contractors for work in the Iraq theater since the invasion of Iraq in 2003 is probably much higher. If spending for contractors continues at about the same rate, by the end of the year, an estimated $100 billion will have been paid to military contractors for operations in Iraq.