IAEA worried about North Korea, US suspects more nuclear-weapon sites

The UN nuclear watchdog chief and the West voiced deep concern about North Korea's expanded nuclear programme on Thursday, with Washington warning that the secretive state may be hiding even more atomic sites.

North Korea boasted about its nuclear advances earlier this week, saying it was operating a uranium enrichment plant with thousands of centrifuges. If confirmed, such a facility could offer it a second pathway to make a nuclear bomb.

"These developments... are a clear manifestation of the risks posed by North Korea's defiance of its international obligations and commitments," US envoy Glyn Davies told an International Atomic Energy Agency (IAEA) meeting in Vienna.

He said in a speech to the IAEA's 35-nation governing board that it was likely Pyongyang had been pursuing enrichment capability before April 2009, the date it most recently claimed.

"If so, there is a clear likelihood that (it) has built other uranium enrichment-related facilities in its territory," Davies said.

Details about North Korea's uranium enrichment activities surfaced last month in a report by a US nuclear scientist who had been invited to the country. He said he had seen hundreds of centrifuges and had been told there were more, which the North Koreans said were operating.

Centrifuges are devices that spin at supersonic speed refine uranium so that it can serve as fuel for nuclear power plants or, if refined to a much higher degree, for atomic bombs.

Tensions rise
North Korea said its enrichment work was aimed at atomic power production, but it already has a plutonium-based nuclear device and carried out two nuclear test explosions in 2006 and 2009. So far it has not shown that it has a working, deliverable nuclear bomb.

IAEA Director General Yukiya Amano expressed "great concern" about reports of the new uranium enrichment facility and construction of a light water reactor in North Korea.

The country has refused full IAEA oversight since 2002 and expelled inspectors last year, leaving the Vienna-based agency with little means to assess its latest nuclear claims or to pressure it into opening up its work to UN monitoring.

The nuclear revelations compounded tensions on the Korean peninsula which have been running high since Pyongyang fired an artillery barrage at a South Korean island, killing four people.

At the IAEA meeting, the European Union urged North Korea to halt construction work on its nuclear facilities and to "refrain from taking any further actions that would increase tensions in the region."

Some analysts say the attack was Pyongyang's attempt to force the resumption of international negotiations that could bring it aid. Others saw it as an attempt to boost the military credentials of the country's leader-in-waiting, Kim Jong-un, the youngest son of ailing leader Kim Jong-il.

Six-party talks aimed at stopping North Korea''s nuclear programme were suspended in December 2008 after Pyongyang walked out.