North Korean leader Kim Jong-Il and his son and heir apparent celebrated the "successful" outcome of his trip to China last week, state media said Sunday, without elaborating on what was achieved.

The North held art performances celebrating the accomplishments of his visit and watched by Kim and his youngest son, Jong-Un, as well as senior officials of the communist regime, Pyongyang's Korean Central News Agency said without saying when it took place.

"A music and dance performance was given... on his successful unofficial visit to the People's Republic of China," KCNA said, describing the trip "historic" and "fruitful" without elaborating further.

It said Kim's tour made an "undying contribution" in boosting ties between the two communist neighbours.

It is rare for Pyongyang to stage such a large public celebration of a trip to China by the leader, who has made seven visits to the neighbouring country since 2000, South Korea's Yonhap news agency said.

Kim, making his third trip in just over a year to China, toured the northeast and east as well as Beijing, where he met President Hu Jintao and other top officials.

The 69-year-old's trip to China, the impoverished but nuclear-armed state's sole major ally and economic prop, was aimed at garnering more aid and Beijing's support for the hereditary power transfer to Jong-Un, experts said.

Jong-Un, believed aged around 27, was made a four-star general and given key posts at the ruling communist party last year in a sign of the youngest son's status as heir apparent.

China has pressed the North to return to six-nation nuclear disarmament talks and to ease tensions with South Korea. It also wants its ally to undertake a Chinese-style opening-up of the state-directed economy.

But it was unclear immediately what Kim's trip achieved on any of the issues, with official media in Pyongyang and Beijing putting a different gloss on Kim's talks with Hu on Wednesday.

China's Xinhua news agency said Kim called for a quick resumption of the long-stalled nuclear disarmament talks, and expressed hope for better ties with South Korea.

But KCNA said only that the two leaders agreed that denuclearisation "on the whole Korean peninsula" was in the region's interests.

KCNA also said Kim praised China's "dynamic progress" but gave no hint on whether his own country would follow suit in opening up its faltering state-led economy.

Analysts say Kim's isolated regime fears the loss of political control this would entail.