Lawyers for the families made the accusations in court documents but identified the source of the information only as former employees. They said officials at the company's North Carolina compound shredded documents related to ongoing investigations sometime around March 18.
Company lawyers had no immediate comment Friday night, but they are quoted in court documents as saying Blackwater took appropriate steps to make sure documents were not destroyed.
Lawyers for the Iraqis do not say what investigation the documents relate to. Blackwater, a major security contractor in Iraq, is under scrutiny in several matters.
Most notably, its guards are under investigation for a September shooting that left 17 Iraqi civilians dead. There is no indication the Justice Department is investigating shredding as part of that case.
Family members are already suing the company for alleged wrongful death in connection with the September shooting, and they asked a judge Friday to let them add document destruction to that lawsuit.
The families also say Blackwater destroyed evidence by repainting and repairing its trucks after the shooting. The company has said the work was done to protect the guards from retribution and was approved by the State Department.
© 2008 Associated Press