Two US firms hired to help interrogate Iraqi prisoners have been sued for allegedly conspiring to abuse detainees in order to boost profits.
The companies deny involvment in the abuse of Iraqi prisoners
The lawsuit, filed on behalf of nine Iraqis, seeks compensation payments and calls for the companies to be barred from future government contracts.
The firms - Titan and CACI International - deny the allegations.
Titan described the lawsuit as "frivolous," while CACI said it was "irresponsible and outrageous."
"Titan never had control over prisoners or how they were treated," Titan spokesman Wil Williams said.
The lawsuit alleges that Titan and CACI employees conspired to torture prisoners in order to obtain more information from them, thereby increasing their chances of winning more government contracts.
"We believe that CACI and Titan engaged in a conspiracy to torture and abuse detainees and did so to make more money," said human rights lawyer Susan Burke, who helped file the lawsuit.
San Diego-based Titan and CACI, of Arlington, Virginia, are accused of breaching the Racketeer Influenced and Corrupt Organizations Act (RICO), a law originally designed to defeat organised crime.
The lawsuit, filed in San Diego, details fresh allegations of grave abuse, with one plaintiff claiming that he was forced to watch while his father was tortured so badly that he later died.
It does not identify specific Titan or CACI employees as the perpetrators.
The accusations are bound to stir fresh controversy over the role of private civilian contractors hired to work on behalf of coalition forces in Iraq.
A surge in the number of contractors performing military duties in Iraq has raised concerns that the companies they work for are not regulated tightly enough.
The lawsuit against CACI and Titan is the most high-profile attempt so far to hold private contractors to account for alleged misdeeds.
The allegations are also likely to reawaken concerns over the abuse of Iraqi prisoners, first highlighted in a series of photographs leaked to the media two months ago.