NEW ORLEANS — Huntington Ingalls Industries Inc. has disclosed a federal civil investigation into allegations that its former parent — defense giant Northrop Grumman Corp. — used Hurricane Katrina relief funds to improperly recover shipbuilding costs. In its latest quarterly filing with the Securities and Exchange Commission, Newport News, Va.-based Huntington Ingalls said it is cooperating with the investigation and denies the allegations. According to the filing, Huntington Ingalls is targeted by a whistleblower suit filing asking for at least $835 million. The company denies the allegation.

The filing does not disclose what shipyards may be involved. Huntington Ingalls owns yards in Pascagoula, Miss., and Avondale, La.