SEOUL (Reuters) - Secretive North Korea boasted advances in its nuclear program on Tuesday, making sure it held the world's attention, 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 U.S. 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 that some Chinese officials did not view North Korea as a useful ally and would take no action if it collapsed.
The United States kept up pressure on China to use its influence with North Korea.
"The Chinese have a duty and an obligation to greatly impress upon the North Koreans that their belligerent behavior has to come to an end," White House spokesman Robert Gibbs said. "I think you'll see progress on multilateral discussions around this over the next few days."
By staging provocations and flexing its nuclear muscle, 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, analysts say.
Andrei Lankov, a North Korea expert at Seoul's Kookmin University, said Pyongyang was simply following a typical pattern.
"For the last two years, both Washington and Seoul have tried to ignore them, so now they use both artillery and centrifuges to say: 'We are here, we are dangerous, and we cannot be ignored. We can make a lot of trouble, but also we behave reasonably if rewarded generously enough'," Lankov wrote on the East Asia Forum website.
North Korea has conducted two nuclear tests to date and is believed to have enough fissile material from its plutonium-based program to make between six and 12 bombs.
It is impossible to verify the North's uranium enrichment program, which it first announced last year. International inspectors were expelled from the country last year, but Washington has said since 2002 that it suspected Pyongyang had such a program.
Analysts say its actions are also linked to family politics, as ailing leader Kim Jong-il seeks to burnish a military image for his inexperienced son and chosen successor Kim Jong-un.
South Korea's Foreign Ministry said on Tuesday the North's nuclear program, last week's attack on Yeonpyeong island and a Chinese proposal for emergency talks would be raised at meeting of foreign ministers in Washington in early December.
South Korea, Japan and the United States, three of the six countries involved in the on-off disarmament talks, will attend.
Talks host China has proposed a summit meeting of the six parties that have been trying to rein in North Korea's nuclear program. Russia and North Korea are also part of that group.
"Returning to consultation and talks is in the interests of all sides," Chinese Foreign Ministry spokesman Hong Lei said at a regular news briefing.
"Ensuring the peace and stability of the Korean peninsula is the shared responsibility of all sides. We call on all sides to do more to stabilize the situation."
Japan's Kyodo news agency quoted diplomatic sources in Beijing as saying Chinese State Councilor Dai Bingguo, who advises leaders on foreign policy, would visit North Korea as early as Wednesday, likely to urge North Korea to take part in the talks.
South Korea has already said now was not the time for talks. Kyodo quoted Akitaka Saiki, Japan's chief envoy to the six-party talks, as also saying it was too soon for talks.
The new Wikileaks revelations, purporting to be from U.S. State Department cables and published by several Western papers, raised questions about the future of the relationship between China and North Korea described in the past as being as close as "lips and teeth."
In one cable by the U.S. ambassador to Seoul, a top South Korean official is described as saying in February that some Chinese officials would not intervene if North Korea collapsed.
U.S. Ambassador Kathleen Stephens wrote that Chun Yung-woo, then the vice foreign minister for South Korea, said the younger generation of communist leaders in China would not risk new armed conflict on the Korean Peninsula, the Guardian reported.
Some analysts were skeptical.
"My personal advice is that the report has been misplaced," said Wang Dong, a professor at Peking University. North Korea is a strategic question for China, not a financial or economic one. He said they have made a mistake about China's viewpoint.
The United States wants Beijing to use its leverage to restrain its ally North Korea, whose shelling of Yeonpyeong last week was the first attack on civilians on South Korean soil since the end of the Korean war in 1953.
The U.S. and South Korean militaries started a third day of large-scale joint exercises off the peninsula's west coast on Tuesday in a show of force they say is meant to deter Pyongyang from staging further provocations.