North Korea's Kim seeking lifeline in China

China has propped up the North's leaders for decades. Analysts say even though Beijing is increasingly fed up with its provocative neighbour, it is willing to bankroll Kim to prevent chaos on its border.

Kim, aware of Beijing's predicament, will demand sweeteners to rein in his military and return to international nuclear disarmament talks hosted by Beijing, analysts said.

He crossed into China in the predawn hours in his armoured train and went to the thriving port city of Dalian, Yonhap news agency quoted South Korean officials as saying.

In his last trip in 2006, Kim toured China's industrial centres for a first-hand look under the hood of the country's quickly growing economy.

Dalian, a rebuilt rust-belt city that has attracted major foreign investment, is a symbol of development that Beijing's leaders have advocated for years to Kim and his father, state founder Kim Il-sung, to revive the North's moribund economy.

But Kim has painted himself into a corner.

Economic reforms would open his hermit state and could undermine his "military first" ideology, which justifies economic hardships at home to build a military strong enough to prevent an invasion.

A booking agent at the Furama Hotel in Dalian where Kim was thought to be staying told Reuters it was not accepting reservations for Monday because of "an event."

A highway into Dalian has been blocked to normal traffic and there was a heavy police guard near a factory zone.