North Korean leader Kim Jong-Il said the isolated state remains committed to nuclear disarmament, Pyongyang's official media reported Saturday, a year after quitting talks on its atomic arsenal.

During a visit this week to Beijing, he also said ties with China will be unchanged by the "replacement of one generation by a new one," amid reports he is paving the way for his son to take control of the isolated communist state.

North Korea, which has tested two nuclear bombs, last year bolted from six-nation talks but in remarks reported Saturday, Kim "expressed the DPRK's (North Korea's) willingness to provide favourable conditions for the resumption of the six-party (disarmament) talks."

He said the North "remains unchanged in its basic stand to preserve the aim of denuclearising the Korean peninsula, implement the joint statement adopted at the six-party talks and pursue a peaceful solution through dialogue."

The comments, carried by the Korean Central News Agency (KCNA), came with the first North Korean confirmation of a secretive five-day trip to China and echoed statements reported by official Beijing media on Friday.

"Both sides decided to make joint efforts to attain the objective of denuclearising the peninsula in accordance with the stand clarified in the September 19 joint statement," KCNA said, referring to a 2005 agreement under which North Korea agreed to give up its nuclear programme in return for badly needed aid and security guarantees.

Professor Koh Yu-Hwan of Dongguk University said Pyongyang was unable to promise to return to the talks in more explicit terms due to the unexplained sinking of a South Korean warship near the border with the North in March.

South Korea and the United States indicated that the resumption of talks with North Korea, also grouping China, Russia and Japan, should wait for the outcome of an investigation into the sinking, which claimed the lives of 46 sailors.

"This is a step forward for the North which in the past said it would not come to the dialogue table unless its demands for a peace treaty with the United States and lifting of UN sanctions are met," Koh said.

Referring to close ties with Beijing, Kim, who himself inherited control of the nation from his father Kim Il-Sung, made comments likely to stoke speculation that he is grooming his third son, Jong-Un, for succession.

The bilateral friendship will remain unchanged "despite the passage of time and the replacement of one generation by a new one," Kim said.

Hu, speaking at a state dinner hosted in Kim's honour, said the two countries should maintain and improve the traditional friendship "along with the passage of time and convey it down through generations," KCNA reported.

Professor Kim Yong-Hyun, also of Dongguk University, said expressions of bilateral friendship lasting for generations were commonly used at summits between the two countries.

"However, it is noteworthy that this rhetoric was repeated at a time when the North is believed to be raising Jong-Un as an heir," he told AFP.

"I wouldn't be surprised if the North Koreans, during the visit, briefed the Chinese side on their plan for a possible succession by the son and Chinese people listened to them carefully."

Succession speculation has intensified since Kim senior, 67, reportedly suffered a stroke in August 2008. He is widely thought to have chosen Jong-Un to inherit power.

Information is scant about Jong-Un, the second son of Kim Jong-Il's third wife Ko Yong-Hee. Some reports say Jong-Un, born in 1983, attended an international school in the Swiss city of Berne under a pseudonym.

Kenji Fujimoto, a former personal chef to Kim Jong-Il, has described the son as "a chip off the old block" who closely resembles his father physically and in terms of personality.