Pakistani nuclear scientist Abdul Qadeer Khan has reportedly told the Washington Post that North Korea may have been enriching uranium on a small scale with "three-thousand or even more" centrifuges in 2002.

Khan added that Pyongyang has constructed a plant to manufacture a gas needed for uranium enrichment as early as the 1990s and that Pakistan helped the North with vital machinery, drawings and technical advice for at least six years.

The North's deputy ambassador to the United Nations, however, claimed in April that his country launched a uranium enrichment program only after the U.S. stepped up its hostile policy towards the North.