The talks mark the first direct involvement of Russia in international efforts to resolve the North Korean crisis -- Moscow had until now been excluded from negotiations despite its privileged access to Pyongyang.

Russia for the first time will join the United States, Japan, China and the two Koreas for more formal three-day talks that are tentatively set for August 27 in Beijing.

Moscow had backed its Soviet-era ally Pyongyang's stance in its escalating standoff with Washington by urging US officials to hold one-on-one talks with North Korea and to offer the hermetic Stalinist state a formal security guarantee.

"North Korea's demands for a security guarantee are absolutely logical and they will probably continue to insist on them" at the Beijing talks, Deputy Foreign Minister Alexander Losyukov told ITAR-TASS.

He also cautioned against the idea of applying economic sanctions against Pyongyang -- a move that North Korea warned would amount to a formal declaration of war.

"We think that sanctions should be applied only in extreme circumstances," said Losyukov.

"Before speaking of any specific measures, we must hold a calm discussion, creating an atmosphere of trust," Russia's top diplomat on Asian affairs said.

An unnamed diplomatic source told the Interfax news agency that Moscow may propose the idea of introducing an international security guarantee for North Korea at the Beijing meeting.

"This document could include even four sides -- North Korea, the United States, Russia and China -- or six sides that would also include Japan and South Korea," the unnamed senior Russian diplomat said.

It was the second time this week that Russia had floated the idea.

But it clashes with the stance firmly taken by Washington.

The United States argues that it has no intention of attacking Pyongyang and that any written security guarantee would amount to giving in to "nuclear blackmail."

North Korea did a dramatic about-turn on July 31 by dropping its demand for direct talks with the United States and agreed to a multi-lateral format under the condition that Russia was also joined the negotiating table.

But it still insists on security guarantees and said in a terse statement issued in Pyongyang that it "will not abandon its nuclear deterrent force" unless Washington began to soften its stance.

The senior South Korean official visiting Moscow said the world should not over-dramatize the North's latest outburst.

The North Korean security demand "will not affect our plans to hold six-way talks in Beijing," ITAR-TASS quoted South Korean Deputy Foreign Minister Kim Jae Sup saying on arrival to the Russian foreign ministry meeting.

Yet Moscow officials cautiously played down the prospects of any breakthrough coming from Losyukov's meetings Wednesday with Kim and North Korea's Vice Foreign Minister Kung Sok-Ung.

All sides concerned have made it clear that officials from the two Koreas will avoid each other in the Russian capital.

The latest North Korean crisis erupted in October when Washington accused the Stalinist state of reneging on a 1994 bilateral nuclear freeze accord by setting up a clandestine atomic program.

North Korea then expelled International Atomic Energy Agencymonitors and withdrew from the treaty.

Pyongyang has since claimed to have reprocessed 8,000 spent nuclear fuel rods at its nuclear plant at Yongbyon.

Washington believes North Korea had extracted enough weapons-grade plutonium for about two nuclear bombs before it froze its Yongbyon plant.

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