A U.N. Security Council committee has been told that North Korea, which has exploded two nuclear devices, may have additional secret atomic facilities, council diplomats said on Monday.
The diplomats told Reuters on condition of anonymity that the assessment was included in a confidential report prepared by the so-called U.N. Panel of Experts, a group that monitors compliance with two rounds of U.N. sanctions against North Korea over its nuclear arms program.
The report to the U.N. North Korea sanctions committee was based on conversations with a U.S. nuclear scientist, Siegfried Hecker, who saw hundreds of centrifuges used to enrich uranium during a rare visit to North Korea last year, as well as the panel's own investigations and analysis, the diplomats said.
"What the report says is that it's not operational," one of the envoys said about North Korea's uranium enrichment program. "They (the panel) are also mentioning other secret facilities."
Details about the additional secret facilities were not immediately available. Much of what is known publicly about North Korean nuclear activities is based on information about the Yongbyon nuclear complex. But United States and its allies have long suspected that North Korea has other facilities.
A South Korean intelligence official said last month that North Korea has been secretly enriching uranium that could be used to build nuclear weapons at three or four undisclosed locations.
North Korea expelled U.N. inspectors from Yongbyon in late 2002 and withdrew from the nuclear Non-Proliferation Treaty, a global pact banning the spread of atomic weapons, several months later.
The panel's report says North Korea's uranium enrichment work — which is in addition to its plutonium-based nuclear arms program that is a subject of international concern — did not start in 2009 but back in the 1990s, the diplomats said.
Pyongyang, they said, has suggested that the program is relatively new.
The report makes a number of recommendations aimed at improving compliance with the U.N. sanctions imposed on North Korea after its two nuclear tests in 2006 and 2009.
Among those recommendations, the diplomats said, was the inclusion of more companies on a U.N. blacklist of North Korean firms supporting Pyongyang's nuclear and missile programs, the diplomats said.
Uranium enrichment could give North Korea a second pathway to fissile material for bombs in addition to its plutonium-based program, which had been frozen under an earlier disarmament-for-aid deal.
U.S. officials said prior to North Korea's 2009 nuclear test that Pyongyang had produced about 50 kg (110 lb) of plutonium, which proliferation experts said would be enough for six to eight nuclear weapons.
North Korea has since said it extracted more fissile material from spent nuclear fuel rods. This could be enough for at least one more bomb.