The Association of National Advertisers Inc. is recommending its members cooperate with an investigation of media-buying practices by the U.S. Federal Bureau of Investigation and Office of the U.S. Attorney General for the Southern District of New York.

ANA CEO Bob Liodice, in a letter emailed to members on Oct. 10, said that the association's general counsel has had "limited discussions" with the FBI thus far. The letter said that the investigator in industrywide probes "often needs assistance in identifying potential victims, witnesses and evidence," and it suggests that advertisers who believe they have been defrauded retain counsel and launch their own internal audits of media-buying contracts.

The Wall Street Journal in September reported that federal prosecutors in Manhattan had begun issuing subpoenas as part of an investigation into media-buying practices, such as agencies receiving rebates from media outlets.

Havas SA, owned by media conglomerate Vivendi SA, is among the companies under scrutiny, according to the Journal.