Vienna: North Korea may have used a "clandestine supply network" to acquire technology and information needed for an uranium enrichment facility the reclusive Asian state revealed late last year, the UN nuclear agency said in a report.
In November 2010, North Korea showed the previously undetected uranium facility in Yongbyon to US expert Siegfried Hecker, who said he was "stunned" at how modern it appeared.
The advance could give the impoverished country a second route to producing nuclear weapons. The North, which carried out nuclear tests in 2006 and 2009, has had a separate plutonium program for decades.
The International Atomic Energy Agency (IAEA), in a 11-page report, said it had interviewed Hecker and carried out a technical review of his observations during his visit to North Korea.
"The layout of the centrifuge cascade and the size of the centrifuge casings observed by (Hecker`s) group were broadly consistent with a design which has been disseminated through a clandestine supply network," the report said.
It added that "information available to the agency indicates that some of the technology and information required for a uranium enrichment program was acquired through" such a clandestine network.
Nuclear experts have previously said the North almost certainly needed help to obtain components secretly for an enrichment site from several sources over many years.
They say the dismantling of a network run by the Pakistani nuclear scientist AQ Khan some seven years ago has not ended the black market in the technology needed for such plants, and that some people linked to that operation may still be active.
In the world`s biggest nuclear proliferation scandal, Khan confessed in 2004 to selling nuclear secrets to North Korea, Iran and Libya.
Centrifuges are finely calibrated cylindrical devices that spin at supersonic speed to increase the fissile element in uranium so that it can serve as fuel for nuclear power plants or, if refined to a much higher degree, for atomic bombs.
The IAEA report suggested that the North had attempted to procure from "a wide range of suppliers material and equipment suitable for use within an enrichment program, such as vacuum components, electronic equipment and dual-use, computer numerically controlled machine tools."
The IAEA`s inspectors were expelled from the North in 2009.
North Korean leader Kim Jong-il told his neighbour and biggest patron China last month that he was willing to return to stalled nuclear talks "without precondition”, China`s Xinhua news agency reported, following a similar pledge to Russia.
China has been pushing its neighbour to resume talks, though Seoul, Washington and Tokyo say that Pyongyang must first show it is serious about denuclearising.
North Korea has flouted past agreements over its nuclear weapons ambitions and is unlikely to give up efforts to build an atomic arsenal it sees as a bargaining tool with the outside world.