The incident added to North Korea's bizarre image just as leader Kim Jong Il was trying to shed its outlaw reputation. Kim depends on foreign aid to feed his starving people, and met this week with European Union officials invited to Pyongyang in hopes of firming up ties with the West.
The man who identified himself to Japanese police as Kim's oldest child, Kim Jong Nam, was reportedly carrying a fake Dominican Republic passport and headed with his 4-year-old son to Tokyo Disneyland, where a ticket costs $45.
Japan deported the man to China, where officials helped him vanish into the fog of secrecy that is North Korea's obsession.
Witnesses said the man and three travelling companions left the commercial flight from Tokyo ten minutes after the rest of the passengers, following its arrival at Beijing's Capital Airport.
He walked down a staircase from an All Nippon Airways jumbo jet to the runway without entering the airport. A van that reporters earlier had seen leaving the North Korean Embassy in Beijing carried him, with two women and a boy, to a VIP entrance.
Then the van departed, leaving no sign where the paunchy, bespectacled man who might be Kim's 30-year-old heir apparent had gone.
Two North Korean embassy cars, with heavily tinted windows, left the airport but there was no sign of the man and his companions turning up at the embassy.
Airport officials said they had no information on the group's travel plans. A diplomat who answered the phone at the North Korean Embassy said, "It's none of your business."
A North Korean diplomat said the Kim Jong-nam story was "a trick" and he was not at the embassy. He did not elaborate.
The first flight to Pyongyang was Saturday on the North's airline, Air Koryo. A woman at the Air Koryo office in Beijing said Kim Jong Nam wasn't on its passenger list. Chinese aviation officials contacted by phone said they knew of no North Korean plans to send a special flight for him.
The Japanese government said the foursome arrived in Japan on Tuesday from Singapore on forged Dominican documents but refused to give other details.
"We cannot confirm that the man is Kim Jong Nam. The government cannot comment because this case involves an individual's privacy," said Kazuhiko Koshikawa, spokesman for Prime Minister Junichiro Koizumi.
However, Japanese media quoted government sources as saying the man claimed he was Kim Jong Nam.
"We had plans to go to Tokyo Disneyland," Kyodo News agency quoted him as saying. He reportedly added that he had visited the park as a teen-ager.
Little is known about Kim's family, and the last publicly available photo of Kim Jong Nam was taken in 1981 when he was a 10-year-old boy.
But according to South Korean officials, Kim Jog Il is believed to have three children: Kim Jong Nam; Kim Sul Song, a daughter born in 1974; and Kim Jong Chul, a son born in 1981. The children all have different mothers.
News reports of the group's detention in Japan added to accounts of lavish living by North Korea's ruling class amid its economic ruin. Aid workers say food shortages caused by bad harvests, coming atop decades of economic mismanagement, have left North Koreans so hungry that many survive by eating tree bark.
The Tokyo Shimbun newspaper quoted unidentified officials as saying the man wore a diamond-encrusted Rolex watch, spent about $80 on lunch and had many $100 bills in his luggage. The report said the women with him carried Louis Vuitton designer bags.
North Korea has long been suspected of topping up its anemic economic income by counterfeiting $100 bills and engaging in drug smuggling.
The episode came amid growing efforts by North Korea to end its diplomatic isolation and seek outside help to stave off economic collapse.
On Thursday, a European Union delegation led by Swedish Prime Minister Goran Persson left Pyongyang following the first visit by a Western European leader.
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