The Y2K watch in the federal government will start on New Year's Eve, at 7 a.m. EST, when New Zealand moves from 1999 to 2000.

On that holiday Friday, a special White House coordination center will start round-the-clock operations to gather massive amounts of information about the Year 2000 computer problem here and abroad.

The center will not act as a command bunker but will send assessments to top-level government officials responsible for responding to Y2K problems in their areas of responsibility, officials said. Also, the center will alert the "help desks" run by major industries and the public about any worrisome electronic disruptions.

In cooperation with other federal technology centers, officials also will watch for what they called "malicious activity around Y2K," ranging from outside cyber attacks on systems to internal malfunctions created through "trap doors" secretly installed by Y2K programmers who had repaired software that might have interpreted "00" in date fields as 1900, not 2000.

"Y2K-related difficulties, however minor, may be happening more or less simultaneously and in multiple locations," said John A. Koskinen, the president's top Y2K troubleshooter. "Much like the computer problem itself, gathering information about systems operations during the date rollover presents the federal government, and the nation, with yet another unprecedented challenge."

Koskinen and other administration officials testified yesterday at a hearing held by the Senate Special Committee on the Year 2000 Technology Problem, chaired by Sens. Robert F. Bennett (R-Utah) and Christopher J. Dodd (D-Conn.). Neither senator objected to the creation of the White House Y2K center, expected to cost at least $40 million, but they urged the officials to use the one-time event to help others learn how to combat future high-tech threats to public and private computer systems.

Koskinen said the Y2K center, called the Information Coordination Center, will initially operate with a core staff of about 40 employees. In the last week of December, as the center gears up for 24-hour monitoring, it will draw on the expertise of about 200 staffers, on loan from several federal agencies, to analyze the data pouring in over the New Year's holiday and the following two weeks.

Koskinen said the center will collect information over the holiday period in five major areas:

* Federal agencies. The agencies will report on the status of 40 safety and health programs considered vital to many Americans. States, meanwhile, have asked for status updates on federal computer systems involving aviation, satellites, the weather and criminal record checks, as well as the U.S. Postal Service and navigable waterways.

* States and localities. The Federal Emergency Management Agency will relay reports from the states, including data on power, telecommunications and health care.

* Private sector. Industry groups will send reports to their appropriate federal emergency operations center, which will analyze, summarize and forward them to the White House center. The electric power industry, for example, will provide data to the Energy Department.

* International. The departments of Defense, State and Transportation will provide information collected from U.S. embassies and other posts overseas.

* Cyber incidents. The National Infrastructure Protection Center at the FBI, the Critical Infrastructure Assurance Office--an interagency group housed at the Commerce Department--and other agencies will be on alert for attacks aimed at compromising systems.