In an announcement that underscores the worries of numerous federal agencies, the Office of Personnel Management said yesterday that it plans to temporarily discontinue its Internet services during the Y2K weekend to protect them from computer hackers, electrical power surges and other possible risks during the New Year's holiday.

Computer users calling up the OPM's World Wide Web home page on their screens will find a special message from the agency's director, Janice R. Lachance, instead of the announcements and links to electronic databases that provide information about federal employment policies, health benefits and pay schedules.

Lachance's message will say that OPM is "taking every precaution to ensure the proper operations and security of the systems that we rely on. As part of this plan, we are temporarily taking our Internet-based systems out of service for several hours over the New Year's holiday weekend," her spokesman, Jon-Christopher Bua, said.

Clinton administration officials said they have not compiled a list of agencies that intend to take their Web pages offline during the Y2K weekend but stressed that each agency can take whatever steps it deems appropriate to ensure the security of its Internet sites and databases.

At the Agriculture Department, the chief technology officer, Anne F. Thomson Reed, said an undetermined number of USDA Web sites will shut down for the holiday. "Some of our sites are more vulnerable than others to hacking attempts and some of them have made the decision to take Web sites down for that critical period, since they don't plan to have people monitoring them every hour for the holiday weekend," she said.

Other agencies, such as the Social Security Administration, said they are studying whether they might need to temporarily suspend access to their Web sites.

The decision is a difficult one for agencies to make. Some officials believe that taking down an Internet site for the New Year's weekend could serve as a challenge to hackers, who might attack the site just before it goes offline or just after it reopens. Other officials say agencies should announce their Y2K precautions in advance as a way of averting the confusion that could result if users try to click on their sites, find them unresponsive and assume they were hit by the so-called millennium bug.

Experts predicted that some companies, universities and nonprofit organizations that plan to close for the holiday also will consider switching off automated equipment to protect against possible power surges or other Y2K-related problems.

Princeton University, for example, said yesterday that it will disconnect its computer system from the Internet for a seven-hour period around the dawn of the New Year, the Associated Press reported.

Bua said Lachance's message will thank electronic visitors for their patience and remind them that "we will use this time to check our systems in order to guarantee delivery of the high-quality service that you expect from us."

The message also will affirm that federal government offices in the Washington area will open as scheduled on Monday, Jan. 3, with all employees expected to report to work on time.

In the event employees hear of Y2K disruptions or face bad weather conditions, the message will recommend that workers pay attention to local news media reports, visit the OPM Web site, at www.opm.gov, or call the agency's hot line, at 202-606-1900.