North Korea is in the final stage of restoring its nuclear facilities, a news report said Tuesday, as leader Kim Jong Il expressed a conditional willingness to end Pyongyang's boycott of international nuclear talks.

South Korean and U.S. intelligence authorities reached the conclusion after scrutinizing about 10 atomic facilities in North Korea since April when the communist regime vowed to restart its nuclear program in anger over a U.N. rebuke of its long-range rocket launch.

Pyongyang claimed the launch was a peaceful attempt to put a satellite into orbit, but the liftoff was widely condemned as a test of the North's long-range missile technology.

The report came as North Korean leader Kim Jong Il told Chinese Prime Minister Wen Jiabao that his country was prepared to return to six-party nuclear disarmament talks depending on progress in its two-way negotiations with the United States.

Kim's comments, carried by official North Korean and Chinese media, were the clearest sign yet that Pyongyang was readying to resume the six-nation talks it withdrew from after conducting missile tests in April and a second nuclear test in May.

The stalled talks involve China, Japan, the two Koreas, Russia and the U.S.

In their meeting late Monday, Kim said that North Korea "is willing to attend multilateral talks, including the six-party talks, depending on the progress in its talks with the United States," China's Xinhua News Agency said in a report issued early Tuesday.

North Korea has long sought one-on-one negotiations with the U.S., claiming that it was compelled to develop nuclear weapons to cope with what it calls the "U.S. hostile policy" and "nuclear threats" against the regime.

Yonhap also cited the government source as saying that North Korea has conducted missile engine tests a few times recently on the country's west coast at a new missile launch site that is in the final stage of construction.

News reports said earlier this year that the North had moved a long-range missile to the new site for a possible test launch, but Yonhap said Tuesday that the missile has been moved elsewhere. The report did not elaborate.

Meanwhile, South Korea's JoongAng Ilbo newspaper reported that the youngest son of Kim Jong Il could be officially named an heir to the communist dynasty as early as next year. The paper cited a South Korean government report to a ruling party lawmaker.

Talk of who will take over North Korea after Kim Jong Il intensified after Kim reportedly suffered a stroke last year. The third son, Kim Jong Un, is widely believed to be the favorite.