SEOUL - NORTH Korean leader Kim Jong Il has nominated his third son as successor and informed the ruling communist party leadership of his choice, South Korea's Yonhap news agency reported on Thursday.

The nomination of Mr Kim Jong Un, 24, was totally unexpected even among party leaders, Yonhap said, quoting 'well-informed intelligence sources'. The reclusive leader 'delivered a directive that he has named Jong Un as his successor to the leadership of the Workers' Party around Jan 8', a source was quoted as saying.

Analysts have said previously Jong Un is not in the running.

'There are different theories but none has been confirmed,' a spokesman for Seoul's National Intelligence Service said.

The succession is a subject of intense interest, notably after South Korean and US officials said Mr Kim Jong Il, 66, suffered a stroke in mid-August.

He is said to be recovering well and still in control of his nuclear-armed but impoverished nation.

Mr Kim Jong Un was born to the leader's third wife, Ms Ko Yong Hi, who reportedly died of breast cancer in 2004. He was educated at an international school in Switzerland but holds no key official posts.

Senior party officials were surprised at the leader's decision, Yonhap said, adding Mr Kim might have pushed ahead due to anxiety about his health.

Mr Kim's eldest son - Jong Nam, 37, who was born to a different mother - is thought by some to have spoiled his prospects after being deported from Japan in 2001 for trying to enter the country with a forged passport.

Some analysts have seen his second son, 27-year-old Kim Jong Chul, as the favourite to take over.

But Mr Kenji Fujimoto, a former Japanese sushi chef for the North Korean leader, has said in a memoir that Mr Kim thought of Jong Chul as too feminine and unfit for leadership.

'This (latest report) is just one of three or four scenarios concerning the succession issue that have been around all along,' said Professor Kim Yong Hyun of Dongguk University.

Mr Jeung Young Tae of the Korea Institute for National Unification (KINU) said analysts should closely watch a March 8 parliamentary election to see whether Jong Un is appointed to the powerful National Defence Commission.

'If that's the case, we can safely say North Korea has started grooming Jong Un as the heir-apparent to his father,' he told AFP.

In a separate report, the state-run KINU said the North is unlikely to experience a sudden collapse despite growing unrest over chronic food shortages. It described leader Kim as fully in command.

'Protracted economic woes have weakened social discipline and stirred discontent among North Korea's citizens, but the predominant view is that it is an over-reaction to read these as signs pointing to North Korea's collapse.'

The North suffered a full-scale famine in the 1990s which killed hundreds of thousands of people, and severe food shortages persist despite foreign aid.

Seoul's state-run Korea Rural Economic Institute said on Thursday the North would run short of one million tonnes of food this year. -- AFP