China's No. 2 leader began a "goodwill visit" to North Korea (searchon Wednesday as efforts mount to convene a second round of six-nation talks on the insular nation's nuclear program -- a parley that would probably be held, like its predecessor, in Beijing.

Wu Bangguo (search), a member of the Communist Party's Standing Committee and head of China's legislature, is heading a state delegation that also includes a vice premier, Zeng Peiyan, the official Xinhua News Agency said. Also aboard: Wang Yi (search), the diplomat who is China's point man on North Korea.

A top-level military official is also on the trip, Xinhua said. The North's official news agency, KCNA, reported the party arrived in Pyongyang late Wednesday morning "at the invitation" of North Korea and was lending support "to the efforts of the Korean people to build a great prosperous powerful nation."

"The two sides are expected to have a friendly and in-depth exchange of views on regional and international affairs and other issues of common interest," Xinhua said. It did not mention the nuclear issue.

The trip by Wu is be the highest-level visit to the North by a Chinese leader in more than two years. It comes as China encourages the reconvening of six-nation talks over the North's nuclear program.

Pyongyang is believed to already have one or two atomic bombs, and recently said it extracted plutonium from its stash of 8,000 spent nuclear fuel rods (searchto build more.

Many believe Beijing, North Korea's most powerful ally, is exerting pressure on Pyongyang through diplomatic channels.

The two countries have taken divergent paths, with China embracing economic reform and opening to the world, and the North remaining reclusive and dogmatic. But KCNA exhorted the two neighbors to draw closer against outside threats. It said the friendship has "long and deep roots" and is "unbreakable."

"The reality today, when the imperialists are making desperate efforts to stifle socialism and complicated problems crop up in the international relations, calls for further developing the tradition of unity and cooperation between ... the DPRK and China," it said. The initials stand for the North's official name, the Democratic People's Republic of Korea.

Washington wants Pyongyang to dismantle its nuclear weapons program immediately.

The North said last week it was not interested in more talks unless Washington agrees to discuss signing a nonaggression treaty barring the United States from launching a pre-emptive attack.

But a few days later, it said it would consider U.S. President George W. Bush's offer for written security assurances to resolve the crisis.

The dual responses are characteristic of the North's delicate game of brinkmanship -- welcoming progress, then rejecting it, then welcoming it again.

China, in its dealings with North Korea, is struggling to balance its duty to its longtime communist ally and neighbor with its deep trepidation at what a nuclear Korean Peninsula might mean for Chinese security. Beijing has long said it wants a nuclear-free Korean Peninsula.

A six-nation summit in Beijing in August brought together the two Koreas, China, the United States, Japan and Russia to discuss Pyongyang's nuclear program. The talks adjourned with no concrete progress but with a promise to meet again -- an agreement that the North since has questioned.

Last week, though, Chinese Foreign Ministry spokesman Zhang Qiyue referred to "the next Beijing talks," implying that China considers them a certainty.