SEOUL North Korea has started to extract plutonium from spent fuel rods at its nuclear arms plant, its foreign ministry said on Saturday, further raising regional tensions already stoked by its defiant rocket launch this month.
The announcement came hours after a U.N. Security Council committee on Friday placed three North Korean companies on a U.N. blacklist for aiding Pyongyang's missile and nuclear programmes, eliciting a sharp rebuke from a North Korean envoy.
Reclusive North Korea has lashed out at being punished for the April 5 launch, widely seen as a disguised long-range missile test that violated U.N. resolutions, saying it would boycott six-way nuclear talks and bolster its nuclear deterrent.
"The reprocessing of spent fuel rods from the pilot atomic power plant began as declared in the Foreign Ministry statement dated April 14," North Korea's official news agency KCNA quoted a foreign ministry spokesman as saying.
"This will contribute to bolstering the nuclear deterrence for self-defense in every way to cope with the increasing military threats from the hostile forces," it said.
In Baghdad, U.S. Secretary of State Hillary Clinton said the United States would not be "blackmailed" by North Korea.
North Korea struck a deal with China, Japan, Russia, South Korea and the United States to disable its Soviet-era Yongbyon nuclear plant in exchange for massive aid and ending its international ostracism.
It has expelled U.N. and U.S. nuclear inspectors at Yongbyon, located about 100 km (60 miles) north of Pyongyang, who had been overseeing steps to put the entire plant out of operation for at least a year.
Speaking at a news conference in Baghdad, U.S. Secretary of State Hillary Clinton urged North Korea to keep its commitment to abandon its nuclear programmes and said she hoped talks on the matter would soon resume.
"We're not going to be blackmailed by the North Koreans," Clinton later told U.S. broadcaster Fox News in an interview taped in Baghdad.
She said the United States and others would ratchet up sanctions to try to prevent Pyongyang from proliferating its nuclear technology.
"We're going to crack down in conjunction with the Chinese, the Russians, the Japanese, the South Koreans and other allies to try to ... tighten the band around North Korea so that they cannot do that," she told Fox News.
Experts said North Korea, which has enough fissile material for six to eight nuclear bombs, wants to separate plutonium from spent fuel rods cooling at the plant that could yield it enough material for at least one more nuclear bomb.
They also said it could take North Korea, which conducted its only nuclear test in October 2006, as little as three months to have the reprocessing facility up and running again.
Other parts of the Yongbyon plant, which includes a nuclear fuel fabrication facility and a reactor, may be beyond repair, they said.
Market players, used to the North's threats, have mostly ignored the latest developments.
But rebuilding parts of Yongbyon could increase the regional security threat because North Korea could add to its meager stockpile of fissile material, increasing the likelihood that it could conduct another nuclear weapons test.
North Korea will stay away from international nuclear disarmament talks, Russia's foreign minister said on Friday after visiting Pyongyang and pressing North Korea to return to the sputtering discussions.
(Additional reporting by Arshad Mohammed in Baghdad)
(Editing by Bill Tarrant)