WASHINGTON - After North Korea relented on nuclear inspection demands, the U.S. on Saturday erased from a terrorism blacklist the communist country President Bush once branded part of an "axis of evil."

The U.S. step, assailed by some conservatives who say it is sketchy and rewards North Korea's bad behavior, is aimed at salvaging a faltering disarmament accord before President Bush leaves office in January.

State Department officials said the inspection agreement and the decision to take North Korea off the state sponsors of terrorism list were in the interests of national security and consistent with the "action for action" principle of the negotiations.

Bush approved the action on Friday and Secretary of State Condoleezza Rice followed suit Saturday.

"Every single element of verification that we sought going in is part of this package," her spokesman, Sean McCormack, told reporters at a rare weekend briefing. The North's removal from the list was effective immediately.

The terrorism designation - now shared only by Cuba, Iran, Syria and Sudan - carries severe penalties. But U.S. officials said North Korea would not see any immediate benefit because it is punished under other programs and could return to the list if it does not comply with the inspections.

The U.S. previously had demanded the six-nation group negotiating with North Korea - China, Japan, North and South Korea, Russia and the U.S. - approved the agreement before the administration would drop the North from the terrorism list.

North Korea will allow atomic experts to take samples and conduct forensic tests at all of its declared nuclear facilities and undeclared sites on mutual consent, according to the accord those countries soon are to formalize. It was not immediately clear if the site of a 2006 nuclear test is a declared site.

The North will permit experts to verify that it has told the truth about transfers of nuclear technology and an alleged uranium program. Officials said North Korea has agreed to immediately resume disabling its main plutonium facility. Since August, the North had reversed that process, heightening tensions.

Officials acknowledged the difficulty in checking North Korea's accounting of its nuclear activities.

"Verifying North Korea's nuclear proliferation will be a serious challenge. This is the most secret and opaque regime in the entire world," said Patricia McNerney, assistant secretary for international security and nonprofileration.