A House oversight subcommittee said Wednesday that it has begun a wide-ranging investigation into allegations that private security companies hired to protect Defense Department convoys in Afghanistan are paying off warlords and the Taliban to ensure safe passage. 'If shown to be true, it would mean that the United States is unintentionally engaged in a vast protection racket and, as such, may be indirectly funding the very insurgents we are trying to fight,' said Rep. John Tierney, D-Mass., chairman of the House oversight subcommittee on national security and foreign affairs. Two weeks ago, Secretary of State Hillary Rodham Clinton described the same situation before a Senate committee while discussing the truck convoys that bring supplies into landlocked Afghanistan. 'You offload a ship in Karachi. And by the time whatever it is -- you know, muffins for our soldiers' breakfast or anti-IED equipment -- gets to where we're headed, it goes through a lot of hands,' she said. 'And one of the major sources of funding for the Taliban is the protection money.' A preliminary inquiry by Tierney's investigators determined that the allegations warranted a full-scale inquiry, focused initially on eight trucking companies that share a $2.2 billion Defense Department contract to carry goods and material from main supply points inside Afghanistan -- primarily Bagram air base -- to more than 100 forward operating bases and other military facilities in the country. The eight companies have completed 40,000 missions since May, carrying food, water, fuel, equipment and ammunition, according to Tierney. The congressman has written Defense Secretary Robert Gates requesting records on all the trucking contractors as well as their subcontractors and expenses for convoy security. In addition, he has sought the records of the Armed Contractor Oversight Directorate, the unit within the military's Afghanistan command that is responsible for overseeing private security companies. Tierney sent letters Wednesday to the companies that share the trucking contracts, three of which have offices in the Washington area. Tierney is seeking access to their records for the contracts, including those related to security and their possible use of licensed or unlicensed private security providers. He has requested that the documents be provided by Jan. 15. One of the companies, NCL Holdings, in suburban McLean, Va., was awarded a two-year trucking contract this year that could reach $360 million. The company's chairman and chief operating officer is Hamed Wardak, the Georgetown-educated son of Afghan's defense minister, Rahim Wardak. NCL Holdings also has a five-year contract to provide guard services. The two other area companies are Anham, of suburban Vienna, Va., and the Sandi Group, of Washington. Anham was formed in 2004 and today, according to its Web site, has close to $1 billion worth of contracts in Iraq. The Sandi Group has worked in a variety of capacities in Iraq, including training security forces in partnership with DynCorp. Phone calls to NCL Holdings, Anham and the Sandi Group were not immediately returned. 