(Adds arrival)

By Jon Herskovitz and Kim Junghyun

SEOUL, Sept 5 (Reuters) - South Korea's chief nuclear envoy on Friday pressed North Korea to halt plans to rebuild a mothballed nuclear plant that makes arms-grade plutonium and instead return to the bargaining table.

Envoys from regional powers called hastily arranged meetings in Beijing from Friday to discuss the secretive North's move earlier this week to take the initial steps of restarting its ageing Soviet-era nuclear plant.

"This is a critical moment and we should try to break this deadlock as soon as possible so that North Korea can promptly restart nuclear disarmament and come back to the six-party talks," Kim Sook said before leaving for the Chinese capital.

North Korea started to disable the Yongbyon facility in November, but halted the process last month, angered by Washington's failure to drop it from the U.S. list of state sponsors of terrorism.

The United States said North Korea must first agree on a system to verify Pyongyang's disclosures about its nuclear programmes.

Kim later arrived in Beijing where he planned to meet the nuclear envoys from the United States and Japan on Friday and then China's envoy on Saturday.

In a briefing Kim held with South Korean media on Thursday, local reporters quoted a government official as saying North Korea was gathering the debris from the reactor's cooling tower, toppled in June as part of the disablement process.

South Korea's foreign ministry barred foreign media from Kim's briefing.

The United States has been in "near daily" contact with North Korea on how to verify the contents of a declaration on its nuclear inventory submitted in June and is open to the two sides meeting in Beijing this week, a senior U.S. official said on Thursday. [ID:nN04388248]

The official said the contacts, including the most recent, which took place on Wednesday, are one reason Washington is not unduly disturbed by Pyongyang's decision to take out of storage equipment at the nuclear complex.

Analysts said the North might be trying to pressure the outgoing Bush administration as it looks for diplomatic successes to bolster its legacy. The North might also believe it can wait for a new U.S. president to try to get a better deal.

U.S. officials, who spoke on condition of anonymity, have said they viewed North Korea's moves more as a negotiating tactic than a genuine effort to rebuild Yongbyon, which proliferation experts believe has produced enough plutonium for six to eight bombs.

The North has completed most of the required disablement steps, which are designed to put it out of the plutonium production business for at least one year. In return, Pryonyang was promised economic aid and political concessions. (Additional reporting by Arshad Mohammed in Washington) (Editing by Jonathan Hopfner and Jeremy Laurence)

AlertNet news is provided by