Extra tree-t at Rock Ctr.

The Rockefeller Center Christmas tree will stay lit a half hour longer Wednesday as cops tighten security measures for the annual tree-lighting event, officials said.

The tree will be unveiled in its illuminated glory at 9:30 p.m. and stay on until about 11:30 p.m. — a half hour longer than last year, NYPD Chief of Patrol Rodney Harrison said Tuesday.

The tree-lighting ceremony is set to begin at 8. The tree will remain lit at night through Jan. 7.

Spectators planning to view the tree lighting should expect to undergo bag checks and wand screenings at the six access points leading toward Rockefeller Center, Harrison said.

“We’re going to have thousands of police officers working,” Harrison said. “Umbrellas, backpacks and large bags or items will be prohibited.”

Currently, no threats have been made against the treelighting ceremony, Harrison said.

Besides additional cops, the NYPD will be deploying K-9 and mounted units, as well as rooftop coverage and cops with rifles.

More than 20,000 people are expected to attend the treelighting ceremony, officials said.