SEOUL, South Korea (AP) - U.N. nuclear experts ordered to leave by North Korea amid an escalating standoff over the regime’s recent rocket launch departed the country Thursday.

Inspectors from the International Atomic Energy Agency left the main site in Yongbyon north of Pyongyang after removing seals and surveillance cameras, a diplomat close to the U.N. agency said Wednesday. He spoke on condition of anonymity because he was not authorized to release the information.

They arrived in Beijing on a flight Thursday from Pyongyang, but declined to speak to reporters.

Four U.S. experts monitoring the nuclear plant in Yongbyon also were preparing to depart after North Korea ordered them out, the State Department said.

The expulsions come after the Security Council unanimously condemned North Korea’s April 5 rocket launch as a violation of previous resolutions barring the North from ballistic missile-related activity. The U.S., Japan and other nations have accused North Korea of using the launch to test long-range missile technology since the delivery systems for sending satellites and missiles are similar.

North Korea, which claims the right to develop a space program, said it launched a satellite into orbit and reacted furiously to the U.N. censure by vowing to boycott international disarmament talks and restart its nuclear program.

Pyongyang conducted a nuclear test in 2006 but later agreed to dismantle its nuclear program in return for shipments of fuel oil under a 2007 deal reached with China, Russia, South Korea, the U.S. and Japan. The process has been stalled since last year by a dispute over how to verify North Korea’s past nuclear activities.

North Koreans, meanwhile, were basking in a two-day holiday celebrating the April 15 birthday of late founder Kim Il Sung.

Kim and his son, current leader Kim Jong Il, are the focus of an intense personality cult in the nation of 24 million people.

APTN in Pyongyang broadcast footage of Kim Jong Il making a rare public appearance for the holiday by joining North Koreans for a celebratory display of fireworks Tuesday night on the eve of his father’s birthday.