North Korea today boasted of advances in its nuclear programme by saying it had thousands of working centrifuges, as pressure built on China to rein in its ally.
Nuclear-armed Pyongyang's revelations about its uranium enrichment, which gives it a second route to make a nuclear bomb, came a week after it fired an artillery barrage at a South Korean island, killing four people, including two civilians.
Experts have voiced surprise at the sophistication of a uranium enrichment plant and light-water reactor at the North's main nuclear complex, which were shown to a US scientist earlier this month. There has been no way to verify the North's claims.
The North is also seen as a proliferation risk, accused by the West of supplying Syria, and possibly Iran, with nuclear know-how.
"Currently, construction of a light-water reactor is in progress actively and a modern uranium enrichment plant equipped with several thousands of centrifuges, to secure the supply of fuels, is operating," the Rodong Sinmun newspaper reported.
"Nuclear energy development projects will become more active for peaceful purpose in the future," added the paper, according the state news agency KCNA.
New revelations by whistle-blower Wikileaks, meanwhile, suggested some Chinese officials did not view North Korea as a useful ally and would take no action if it collapsed.
By staging provocations and flexing its nuclear muscle, analysts say the isolated North is seeking to increase its leverage as it pushes for a resumption of talks with regional powers, which it walked out of two years ago, in return for aid.
Japan's Kyodo news agency has quoted diplomatic sources in Beijing as saying Chinese State Councillor Dai Bingguo, who advises leaders on foreign policy, would visit North Korea as early as tomorrow and likely urge North Korea to take part in the talks.
Reuters