The diplomatic offensive came as the United States said the six-nation talks were the only appropriate forum for negotiations and South Korea said it would urge Beijing to use its influence with Pyongyang to bring the North back in.

The isolated Stalinist regime on Thursday announced it possesses nuclear weapons and was dropping out of the multilateral talks, accusing the United States of planning to invade.

China at the weekend said it would maintain the pressure on the North, with Foreign Minister Li Zhaoxing telling US counterpart Condoleezza Rice that Beijing would keep working to jump-start the talks.

"(China) will strive to make the situation develop in a positive direction so that the six-party talks could resume as soon as possible," Li was quoted by Xinhua news agency as saying in the telephone talks Saturday.

Russia, traditionally considered sympathetic to the North, issued an unusually strongly-worded statement that Pyongyang would have made the "wrong choice" if it decided to quit the discussions.

Russian Defense Minister Sergei Ivanov said at a meeting of security experts in the German city of Munich Saturday: "If the information in question proves accurate, I would say that North Korea has made the wrong choice."

"I believe we should do all we can to keep that state in the treaty framework."

The reactions highlighted growing US-led international pressure on the North since it claimed to have already developed nuclear weapons.

Speaking in Washington, where he has been holding talks with US officials on the standoff, South Korean Foreign Minister Ban Ki-Moon said Seoul would meanwhile try to persuade China to draw the North Koreans back to the talks.

Ban was to meet Rice on Monday to discuss the issue.

"We shared the understanding that China intensify its effort to persuade North Korea and we've agreed to undertake diplomatic efforts toward that goal," Ban was quoted by Yonhap news agency as saying.

China plans to send an envoy to Pyongyang this month in an attempt to get the talks to resume, according to Seoul officials.

Wang Jiarui, head of the International Department of the Chinese Communist Party's Central Committee, will soon visit North Korea to discuss the nuclear issue, Seoul's YTN television said Sunday. Officials in Seoul and Beijing declined to confirm the report.

The nuclear issue is also expected to be a key agenda item when Japan's defense minister and foreign minister visit Washington on February 19.

The United States, the two Koreas, China, Russia and Japan met for three rounds of talks until June last year.

But a fourth round failed to take place as planned in September, with Pyongyang accusing Washington of a "hostile" policy -- among other objections.

The latest nuclear standoff began in October 2002 when Washington accused Pyongyang of operating a secret program based on highly-enriched uranium for weapons, in violation of a 1994 arms control agreement.

Pyongyang denied the US charge but restarted its mothballed plutonium-based nuclear programme to reprocess spent fuel rods at its Yongbyon nuclear complex.

The state of North Korea's nuclear deterrence is nearly impossible to verify. Washington believes that Pyongyang has developed one or two crude nuclear bombs and may have reprocessed enough plutonium for six more.

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