China's top nuclear envoy Wu arrives in N. Korea

China's top nuclear envoy Wu Dawei unexpectedly arrived in Pyongyang on Monday as Beijing steps up its efforts to jumpstart long-stalled six-party negotiations aimed at ending the North's nuclear weapons program.

The visit by Wu, not officially announced by China, comes on the heels of his trip late last month to Washington, almost five years from the six-party talks, which also involve Japan, South Korea and Russia, become deadlocked in December 2008.

North Korea's official Korean Central News Agency reported a Chinese delegation led by Wu arrived in Pyongyang, without giving other details.

While in Washington, Wu discussed the nuclear issue with U.S. officials including Wendy Sherman, undersecretary of state for political affairs, Daniel Russel, assistant secretary of state for East Asian and Pacific affairs, and Glyn Davies, special representative for North Korean policy.

Wu, chairman of the six-party talks, last visited Pyongyang in August, during which he had a meeting with Kim Kye Gwan, the North's first vice foreign minister and its point man on nuclear issues.

China and North Korea have expressed their willingness to resume the multilateral talks at an early date.

At a symposium in September in Beijing to mark the 10th anniversary of the launch of the six-party talks, Kim called for unconditional resumption of the negotiations, while there are signs of renewed activity at North Korea's main Yongbyon nuclear complex.

After the symposium, Ri Yong Ho, Kim's deputy who served as the country's chief envoy to the six-party talks, traveled to Berlin and London, during which he held informal talks with former U.S. government officials, including Stephen Bosworth, who was U.S. special representative for North Korean policy during the first administration of President Obama Barack.

Bosworth and Robert Gallucci, who was also formerly responsible for talks with North Korea, said in an op-ed piece recently published in the International New York Times that Washington should return to the negotiating table with Pyongyang.

But Japan, South Korea and the United States say North Korea must first take concrete steps toward giving up its nuclear ambitions before there can be substantive discussions on restarting the talks.

The United States is planning to hold a meeting with senior Japanese and South Korean diplomats in charge of North Korean affairs on Wednesday in Washington.