In the latest signs of a new era of heightened security in the nation's capital, National Guard soldiers began patrolling the U.S. Capitol yesterday and officials announced that the public's access to the lighting of the National Christmas Tree on the Ellipse will be severely limited.

In years past, hundreds of Washington area families who didn't get tickets to the tree lighting could squeeze into standing-room-only spaces around the fenced-in 40-foot Colorado blue spruce south of the White House.

This year, such tree-gazing will be virtually impossible -- those without tickets will not be permitted inside the Ellipse for the Dec. 6 ceremony because of security concerns following the Sept. 11 terrorist attacks.

"The walk-up public is not allowed this year," said Bill Line, a spokesman with the National Park Service's National Capital Region. "If you don't have a ticket, the wiser idea is probably not to try to venture down."

With a security buffer zone and fencing stretching along the streets surrounding the Ellipse -- Constitution Avenue as well as E, 15th and 17th streets NW -- the view is not likely to be much of a view at all. Park Service officials are also concerned about the safety of people trying to catch a glimpse from the traffic-heavy streets.

Line said sightseers will be allowed inside the Ellipse later that evening, a few hours after President Bush is to push the button that lights up the tree at 6 p.m. The restrictions will apply only to the ceremony itself and will not involve access to Ellipse festivities during the month-long Christmas Pageant of Peace, Line said.

In a more immediate reminder of increased security, about 15 National Guard soldiers took up posts alongside U.S. Capitol Police officers on Capitol Hill about 7 p.m. yesterday, directing traffic, searching vehicles and barring trucks from a 20-square-block area. D.C. police had deputized the first of about 100 soldiers of the D.C. Army National Guard in a morning swearing-in. The deployment relieved Capitol Police officers from 12-hour, six-day-a-week shifts for the first time since Sept. 11.

Separately, Mayor Anthony A. Williams (D) considered a request to Congress to shield the city from liability for the federal assignment. District leaders also detailed a high-level tangle with Guard and Capitol Police officials on the subject, which threatened to torpedo the arrangement hours after it was announced Thursday.

"We obviously had liability concerns because these National Guard soldiers were going to be carrying guns and acting as police officers patrolling public streets, grounds and buildings," Deputy Mayor Margret Nedelkoff Kellems said.

The city wants guarantees that National Guard soldiers will receive D.C. police training, that Congress will indemnify the District or that federal police will deputize the Guard members before the 14-day authority can be extended to what Capitol Police hope will be a 90-day deployment.

As for Christmas tree security, Park Service officials said the decision to restrict attendance was made by the Secret Service. A spokesman for the Secret Service declined to comment, saying that many of the security plans surrounding the festivities have not been finalized.

Each year, thousands attend the tree lighting, a presidential tradition dating back nearly eight decades. The event marks the opening of the annual pageant, for many signaling the official arrival of Washington's holiday season.

About 2,000 free tickets to the tree lighting were reserved by the public Oct. 9 through the Park Service's President's Park office, officials said. Also attending the ceremony will be about 3,000 ticket-holding White House dignitaries and other Washington VIPs. Unlike in years past, the non-ticketed public will not be allowed to take up unfilled bleacher seats.

"There is simply heightened security . . . because of the environment that we're in," said Roland McElroy, executive director of Pageant of Peace Inc., a nonprofit group that oversees the events along with the Park Service. But, he added, "we don't want people to not come down and see the pageant and enjoy it."

The new security restrictions will apply to the tree lighting itself, and not the festivities during the month-long Christmas Pageant of Peace on the Ellipse.