Contractors working for the Pentagon "funneled US taxpayer dollars to Afghan warlords and strongmen linked to murder, kidnapping, and bribery, as well as to Taliban and anti-coalition activities," says a congressional report released Thursday.

A year-long investigation into private contractors in Afghanistan, carried out by the Senate Armed Services Committee, found, among other things, a contractor that had two alleged Iranian spies on its payroll, and another contractor who hired two rival Taliban-linked warlords, only to see one kill the other in an ambush.

The report (PDF, 32MB), which looked at 125 defense contracts over three years, provides further evidence that the coalition war effort in Afghanistan may be becoming a lucrative source of financing for the very groups the coalition is fighting.

Claims that security contractors have been paying bribes to the Taliban have been around for the better part of the year. And this summer the New York Times reported on evidence of "all-out collusion" between some security contractors and Afghan insurgents.

One contractor on which the new congressional report focuses extensively is ArmorGroup, which the report alleges hired two rival warlords, one of them Taliban-linked, to guard the Shindand airbase in Herat province. ArmorGroup referred to the two warlords as "Mr. White" and "Mr. Pink," in reference to the violent criminal characters in Quentin Tarantino's Reservoir Dogs.

Eventually, according to the report, "Mr. Pink" killed "Mr. White" in an ambush, and the contractor was forced to hire a replacement. That replacement, "Mr. White II," was found meeting with a Taliban leader during a coalition raid. Both "Mr. White II" and the Taliban commander were killed.

The report also states that contractor EOD Technology had at least one person on its payroll who was believed by US intelligence to be an agent of a "hostile foreign power."

Parts of the report dealing with this allegation are heavily blacked out, but it appears from the context that the country referred to was Iran, something that was confirmed by ABC News.

Speaking on background, unnamed congressional staffers told ABC that the contracting situation was so chaotic at times that "guards were not given weapons or were provided with defective weapons. ... In one case, a Marine lance corporal was killed by an Afghan insurgent who was employed as a private security contractor on a US military contract."

AmorGroup recently lost a lucrative partial contract to provide security to the US embassy in Kabul, presumably because of earlier allegations that the company had suffered a breakdown in the chain of command that led to "sexual predators and deviants" running "rampant" through Kabul.

But, as Spencer Ackerman notes at Wired, that contract went to EOD Technology, the company mentioned above as having possibly employed an Iranian agent.

“Our reliance on private security contractors in Afghanistan has too often empowered local warlords and powerbrokers who operate outside the Afghan government’s control and act against coalition interests,” Said Sen. Carl Levin (D-MI) in a statement. “This situation threatens the security of our troops and puts the success of our mission at risk.”

Levin continued: “We need to shut off the spigot of US dollars flowing into the pockets of warlords and powerbrokers who act contrary to our interests and contribute to the corruption that weakens the support of the Afghan people for their government."

Levin noted that “this problem clearly has the attention of our commanders on the ground. When he was in command, General McChrystal told the committee that private security contractors are ‘just not right for a country that is growing law and order.’ And General Petraeus recently told the committee that our use of private security in Afghanistan should be limited to ‘legal, licensed and controlled’ contractors."