Kim Jong-il alone to decide North Korea successor

"Nobody can assert anything... My father will only decide," Kim told reporters upon arriving at a Beijing airport, when asked about the next leader of the communist country.

Last week, South Korean news agency Yonhap reported that Kim Jong-il, thought to be recovering from serious illness, had picked his third and youngest known son, Jong-un, to succeed him.

Japan's NHK public TV showed Kim Jong-nam, wearing a baseball cap and sunglasses, at Beijing airport.

Kim was in the Chinese capital for a couple of days "on leisure for personal events," Yonhap quoted him as saying. He planned to travel to another country after China before returning to North Korea in a couple of weeks, the report said.

Friday, Kim Jong-il met a senior Chinese official in Pyongyang in his first reported meeting with a foreign dignitary since a suspected stroke in August.

Analysts had said a meeting with a foreign visitor would offer evidence that Kim, who U.S. and South Korean officials said fell seriously ill last year, was well enough to run Asia's only communist dynasty and make decisions about its nuclear program.

The demise of the 66-year-old Kim without a clear successor could likely add to the uncertainty of a country trying to develop nuclear weapons but with an economy in ruins and a population constantly on the edge of famine.

The question of succession in the secretive communist state is so closely guarded that no-one outside Kim's immediate circle of family and confidants is thought to have any clear knowledge of the situation.

But speculation about his health and the succession is a favourite topic in South Korea.

"I can't speak about such a sensitive issue," the eldest son said, when asked about the health of the North Korean leader.

(Reporting by Angela Moon and Linda Sieg in Tokyo; Editing by Alex Richardson)