Federal investigators stepped into the fray surrounding Hewlett-Packard Co.’s possibly illegal investigation of media leaks, as the company’s board planned to meet again to discuss the fate of embattled Chairwoman Patricia Dunn.

HP revealed in a Securities and Exchange Commission filing Monday it had been “informally contacted” by the U.S. Attorney’s Office for the Northern District of California concerning the company’s methods for rooting out who was giving confidential company information to journalists.