Russia's foreign minister has urged North Korea to return to six-nation disarmament talks on Pyongyang's nuclear programmes. The foreign ministry statement says Sergey Lavrov told his North Korean counterpart, Pak Ui Chun, about Russia's “serious concern” over North Korea's new uranium enrichment facility.The North Korea claimed it has recently completed 2,000 centrifuges that can help enrich uranium for a new reactor.Pyongyang had agreed to dismantle its nuclear programmes in return for aid and other concessions before the talks stalled last year after the nation conducted its second nuclear test.