Another North Korea provocation, but no crisis: US envoy

The United States accused North Korea of being a danger to the region after it showed off its latest advances in uranium enrichment but its envoy said on  Monday Washington was open to talks with the isolated state.

The reported sighting of over a thousand centrifuges at  its main nuclear complex appears to confirm that the impoverished North is on the way to creating a second source  of weapons-grade nuclear material.

It comes just as Pyongyang is pressing regional powers to resume talks on its atomic weapons programme -- about the only real leverage it has with  the outside world.

"It is the latest in a series of provocative moves by the  DPRK ... it is a very difficult problem we have been  struggling to deal with for 20 years," US envoy Stephen Bosworth told reporters in Seoul, referring to the North by  its acronym.

"This is not a crisis, we are not surprised," said  Bosworth, who is on the first leg of a tour of east Asia.

"My crystal ball is foggy but I would never declare any process dead," he said when asked about the fate of regional six-party talks. "We have hope that we will be able to resuscitate (them)."

The North's reported nuclear advances come nearly two months after Kim Jong-il started the transition of power to  his youngest son, Kim Jong-un. Analysts say he also wants to  use nuclear muscle to boost his son''s credentials with the  military.

Washington is particularly worried by the threat of North Korea -- whose ravaged economy has long relied heavily on arms  exports -- selling nuclear weapons material to other states. It has conducted two nuclear tests to date and is believed to  have enough fissile material to make several nuclear warheads.

The latest flurry over Pyongyang's nuclear ambitions follows comments at the weekend by Siegfried Hecker of  Stanford University that he had been shown more than a thousand centrifuges at the Yongbyon nuclear complex this  month. North Korea said they were operational.

It is impossible to verify the North's claims, which it  first announced last year. International inspectors were expelled from the country last year, but Washington has said since 2002 that Pyongyang had such a programme.

The North has said it wants to resume multilateral talks, but Washington and Seoul have said they will only consider return to the negotiating table when Pyongyang shows it is sincere about denuclearisation.

By showing its nuclear hand, analysts say North Korea is seeking to gain leverage in any aid-for-disarmament negotiations in stalled six-way talks with regional powers China, Japan, South Korea, Russia and the United States.

A South Korean unification ministry official in Seoul said the latest revelations, if true, posed "a very serious problem", a view echoed by Japan, the next stop on Bosworth's  trip.

"We absolutely cannot accept North Korea moving forward with nuclear development from the viewpoint of our country's  security as well as the region's peace and stability," Japanese chief cabinet secretary Yoshito Sengoku told a news  conference.

Admiral Mike Mullen, chairman of the US military's joint chiefs of staff, said major powers must work together to put pressure on North Korean leader Kim Jong-il.

In particular, he said China -- North Korea's closest ally  -- would have "an awful lot to do with" future attempts to  sway Pyongyang. Bosworth is due in Beijing on Tuesday.

Mullen put the nuclear disclosure in context by pointing to the March sinking of a South Korean warship, which Washington and Seoul blame on Pyongyang. The suspected torpedo attack killed 46 South Korean sailors and stoked tensions on  the peninsula.

"All of this is consistent with belligerent behaviour --  the kind of instability creation in a part of the world that  is very dangerous," he said.

The North Koreans told Hecker they had 2,000 centrifuges in operation, but the US team that visited the country was  unable to verify that they were working. Hecker said North Korea described the programme as aiming to generate  electricity.

US defence secretary Robert Gates dismissed the notion the enrichment programme might be for energy production,  saying North Korea had a nuclear arms programme for some time and probably had a number of nuclear devices.