In a statement adopted by consensus, the International Atomic Energy Agency's (IAEA) 35-nation board of governors "expressed its serious concern" over North Korea's announcement February 10 "that it would suspend its participation in the six-party talks for an indefinite period, and that it had manufactured nuclear weapons."

North Korea upped the ante on Thursday. It said the moratorium on testing long-range missiles it had agreed to in September 1999 when Bill Clinton was US president was rendered invalid by George W. Bush cutting off bilateral talks on missiles when he took office in 2001.

The announcement came a day after North Korea, a self-proclaimed atomic power, demanded the United States apologise for calling it part of an "axis of evil" and one of the "outposts of tyranny" before it would return to the talks.

The United States on Thursday criticized North Korea's decision to end its missile-testing moratorium, saying the move threatened regional stability and deepened Pyongyang's isolation.

"This is not helpful. It does not serve North Korea's interests and the interest of peace and stability in the region," said a State Department official, who asked not to be named.

The IAEA said in its statement Thursday that it "strongly encouraged all the parties concerned to redouble their efforts to facilitate an early resumption of the six-party talks with a view to achieving a peaceful resolution of the DPRK (North Korea) nuclear issue," according to a copy of the text given to the press.

The statement "urged particularly the DPRK to agree to the resumption of the six-party talks... without preconditions."

It also "urged the DPRK to completely dismantle any nuclear weapons program under credible international verification."

The board "emphasized the importance of continued dialogue to achieve a peaceful and comprehensive resolution of the DPRK nuclear issue and attached great importance to the crucial role played by the six party talks in this regard."

The statement was written by the five nations on the IAEA board which are involved in the six-party talks -- China, Japan, South Korea, Russia and the United States, diplomats said.

IAEA chief Mohamed ElBaradei had Monday said North Korea's declaration that it has nuclear weapons "is a matter of the utmost concern and has serious security implications and highlights yet again the importance and the urgency of finding a diplomatic solution through dialogue."

North Korea kicked IAEA inspectors out in December 2002 and withdrew from the nuclear Non-Proliferation Treaty (NPT) the following month.

US officials say North Korea's missile program poses a serious threat to the United States and its allies. North Korea's missile launch in 1998 over Japan prompted Japan to begin researching missile defense.

South Korea's intelligence agency says North Korea is developing rocket engines for its Taepodong-2 missile with a range of 6,700 kilometersmiles), which would be capable of hitting the US state of Hawaii.

However it says North Korea lacks the technology to launch a nuclear-tipped missile.

The nuclear standoff erupted in October 2002 when the United States accused North Korea of operating a program based on highly enriched uranium.

Pyongyang denied that charge but restarted a plutonium-based program frozen under a 1994 arms control agreement.

The two Koreas, the United States, China, Japan and Russia, have met three times since 2003, with the last round held in June.

North Korea boycotted a fourth round scheduled for last September, citing "hostile" US policy.

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