California ? The Securities and Exchange Commission has upgraded its informal inquiry of Hewlett-Packard Co.’s boardroom spying probe into a formal investigation, according to a regulatory filing Thursday.

HP disclosed the development in an SEC filing after reporting financial results for the fourth quarter and the fiscal year 2006.

Palo Alto-based HP also indicated in the filing that it was the target of at least five shareholder lawsuits related to the probe, and had received a request for documents from the Federal Communications Commission.

The computer and printer maker previously had disclosed several governmental inquiries related to the cloak-and-dagger tactics used to identify HP board members leaking information to the media.