New images of North Korea's main nuclear facility show that the isolated regime has apparently produced more plutonium for its weapons programme than previously thought, a US monitor said, as tensions soar over Pyongyang's ambitions. The respected 38 North website, a monitoring project linked to Johns Hopkins university, said Friday that thermal imagery of the Yongbyon nuclear complex appeared to show that Pyongyang had reprocessed spent fuel rods at least twice between last September and June this year. "The Radiochemical Laboratory operated intermittently and there have apparently been at least two unreported reprocessing campaigns to produce an undetermined amount of plutonium that can further increase North Korea's nuclear weapons stockpile," it said.