North Korea's ailing leader Kim Jong-Il emphasised the "rising generation" during a visit to China that analysts said was part of an elaborate transition to his nation's second dynastic succession.

North Korean and Chinese state media late Monday broke their silence on a mystery-shrouded five-day trip by the 68-year-old Kim to northeast China, where he met President Hu Jintao.

China's Central Television quoted Kim as telling Hu his nation was willing to return to nuclear disarmament talks and reduce acute regional tensions. But the North's Korean Central News Agency (KCNA) made no mention of such remarks.

KCNA instead focused heavily on the symbolism of Kim's trip to sites linked to his late father and founding president Kim Il-Sung, a guerrilla fighter against Japan's 20th century colonisation of Korea and northeast China.

Analysts saw Kim's train-and-limousine tour as a bid to confer legitimacy on another father-to-son succession with the "Dear Leader" widely seen as preparing an eventual handover to his youngest son, Kim Jong-Un.

The Swiss-educated Jong-Un, believed aged around 27, could be named to a senior post when North Korea next month holds its first meeting for decades of key communist party delegates.

Hu, at a welcoming banquet on Friday in the northeastern city of Changchun, was quoted by KCNA as wishing a "signal success" to the meeting in the first half of September.

Kim, in his banquet remarks, referred to his father's "hard-fought struggle against the Japanese imperialists" in northeast China.

"With the international situation remaining complicated, it is our important historical mission to hand over to the rising generation the baton of the traditional friendship passed over by the revolutionary forerunners of the two countries as a precious asset so as to carry it forward through generations," he said.

KCNA did not list Jong-Un as part of Kim's delegation, but some South Korean media reports have said he accompanied his father.

After suffering a stroke in August 2008, Kim has accelerated plans for a power transfer in the impoverished communist state, which is heavily reliant on Chinese economic aid and diplomatic backing.

Chinese television showed the North Korean leader, wearing his trademark light-brown suit, looking slightly emaciated and limping a little.

The footage showed a stern-looking Hu urging Kim to push forward economic reforms and modernisation in North Korea, where food shortages are chronic.

According to China's Xinhua news agency, Hu said "economic development calls for self-dependence but cannot be achieved without cooperating with the outside world".

KCNA confirmed that Kim visited a Jilin school where his father studied in the late 1920s, and said he was "overcome with deep emotion". He also toured Changchun and Harbin, among other places, the agency said.

"Kim Jong-Il is making a pilgrimage to all these places to showcase that the upcoming power transfer to Jong-Un is an act of following Kim Il-Sung's legacy," Yang Moo-Jin, of Seoul's University of North Korean Studies, told AFP.

Chinese television quoted Kim as saying that North Korea's stance on ridding the Korean peninsula of nuclear weapons was unchanged and the country "is not willing to see tensions on the peninsula".

Kim pledged to remain in close consultation with China and hoped for the "early resumption" of six-party nuclear disarmament talks that also include South Korea, the United States, Japan and Russia, it said.

China hosts the six-party talks which began in 2003. The North walked out in April 2009 and staged its second atomic weapons test a month later.

The two leaders discussed the March sinking of a South Korean warship that left 46 sailors dead and a subsequent United Nations statement condemning the incident, the Chinese TV report said.

An international panel backed by South Korea has blamed North Korea for the sinking, but Pyongyang has angrily denied involvement and warned that recent US-South Korean military exercises could trigger war.

Amid the tensions between Washington and Pyongyang, the US government on Monday slapped sanctions on four people and eight firms linked to North Korea's government, the Treasury Department said. They will face a travel ban and assets freeze.

According to Xinhua, Hu said stronger communication between Beijing and Pyongyang was of "critical importance to effectively maintaining peace and stability in the Northeast Asia region and to promoting common development".