Pyongyang says plutonium extraction will help “bolster nuclear deterrence”.
But US officials say no satellite has been detected in orbit and the launch was likely a cover for a test of the North’s longest-range ballistic missile.
On April 13 the UN Security Council adopted a presidential statement denouncing the North’s rocket launch and calling for a tightening of sanctions.
The move was quickly condemned by North Korea, which announced a day later that it was pulling out of nuclear disarmament talks and would resume work on building nuclear weapons.
“We will never again take part in such talks and will not be bound by any agreement reached at the talks,” the North’s foreign ministry said in a statement.
North Korea conducted its first and to date only test of a nuclear weapon in October 2006.
The North began disabling its Soviet-era Yongbyon nuclear plant, which produced weapons-grade plutonium, more than a year ago as part of a six-nation aid-for-disarmament deal reached in February 2007.
The deal followed lengthy talks involving envoys from China, Japan, Russia the US and North and South Korea.
But following the UN’s condemnation of its rocket launch North Korea said the denuclearisation process had effectively been “torn apart”, vowing to step up work on its weapons programmes.
Experts say North Korea, which is believed to have enough plutonium for six to eight atomic bombs, could probably extract enough fissile material from existing spent fuel nuclear rods to produce enough for at least one more bomb.