WHEN Kim Jong-il last went abroad, in January 2006, he met each of China's top nine leaders. The North Korean strongman's secret eight-day tour - it took that long because he insists on travelling everywhere by train - was in an "unofficial" capacity and yet he received red carpet treatment, the likes of which no other foreign leader has received in modern times.

Along the way, Chinese Government sources say, Chinese attendants were secretly taking stool samples to analyse Mr Kim's health and life expectancy. But Mr Kim was one step ahead of them, the sources say: he left chemical masking agents in the toilet bowl that made analysis impossible.

Such is the world's fascination with the physical well-being of Kim Jong-il.

Mr Kim's appearance at Thursday's Supreme People's Assembly has again set the world's intelligence agencies alive with speculation about whether the Dear Leader is desperately ill. It was his first public appearance since apparently suffering a stroke in August.

Mr Kim looked frail, his trademark bouffant hair had lost its exuberance and his skin hung loosely off his once-pudgy face.

Video footage showed him limping but still commanding his impoverished nation. The assembly unanimously "re-elected" him to another term as chairman of the National Defence Commission and therefore head of state.

But nobody outside Mr Kim's inner circle can predict how long his body will last.

Analysts agree his death could have profound consequences for the impoverished people of North Korea and for stability across the region.

"I'm not a fortune teller," said Han Beom Wook, director of the Asia Strategy Institute in Seoul. "But if he designates one of his sons as successor then his policies will be continued: proliferating nuclear weapons, counterfeit money and drugs and threatening his neighbours."

If Mr Kim has chosen one of his three sons as successor, such as the eldest, the playboy Kim Jong-nam, or the favoured 26-year-old Kim Jong-un, then he has given no outward sign.

"Kim Jong-il was trained for 25 years before he took his father's job, but nothing like that is happening now," said Andrei Lankov, a North Korea specialist at Kookmin University in Seoul.

Professor Lankov has placed his bets on Mr Kim's brother-in-law, Chang Sung-taek, who at 65 is by far the youngest in North Korea's informal leadership group and who in recent years has appeared prominently by Mr Kim's side.