Kim arrived on the unannounced visit by special train at Beijing railway station early Monday amid tight security, according to South Korean media reports.

He immediately left the station for the Diaoyutai State Guesthouse in Beijing's leadership compound where the summit was expected to take place.

The summit will address Beijing's economic assistance to impoverished North Korea as well as the nuclear standoff, Yonhap news agency said.

Security at Beijing Station was heavy, with armed police officers checking baggage and passenger IDs, Yonhap reported.

South Korean newspapers said Kim would stay in China from Monday through Thursday.

Kim last visited China in January 2001, on a trip that included a tour of Shanghai's stock exchange. On that trip to China and a later trip to Russia in 2002, the reclusive leader travelled by train.

It is Kim's third trip to China as leader of the North Korean regime.

Later Monday Kim plans to tour Zhongguancun Technology Park, Beijing's equivalent of Silicon Valley, and attend a welcoming dinner hosted by Hu, Yonhap said.

China declined to confirm the visit.

"We have no official information," said the foreign ministry.

During his last visit in January 2001 Kim stayed at the North Korean embassy in central Beijing.

There was no special security in place outside the embassy Monday, with the usual two guards at the entrance. They denied any knowledge of Kim's visit.

Embassy staff also refused to confirm he was in Beijing.

China has been hosting six-nation talks to resolve the North Korean nuclear standoff which also bring together the two Koreas, the United States, Russia and Japan.

China has been actively working to persuade North Korea to drop its nuclear plans in return for help for its decaying economy.

A new round of talks is scheduled to take place before the end of June.

Washington demands the complete, verifiable, and irreversible dismantling of North Korea's nuclear programs, both plutonium and enriched uranium schemes, before it will offer concessions to the impoverished state.

A North Korean foreign ministry spokesman issued a statement late Sunday, slamming US Vice President Dick Cheney -- who reaffirmed US demands during a visit to China last week -- as "mentally deranged."

Cheney visited Japan, China, and South Korea last week calling for stepped up support for US forces in Iraq and for the US stand on North Korea's nuclear weapons drive.

Cheney said after talks with Chinese leaders that North Korea could provide nuclear technology to terrorist groups like Al-Qaeda, and warned of a nuclear arms race in Asia if Pyongyang was not stopped.

"(North Korea) considered Cheney as a mentally deranged person steeped in the inveterate enmity towards the system in the DPRK (North Korea) long ago as he is the boss of the neo-conservative forces in the US," the North's spokesman said.

Linking North Korea to Al-Qaeda was "an expression of total ignorance and nothing but a far-fetched attempt to justify" Washington's hostile policy towards Pyongyang," the spokesman added.

"Action is inevitably followed by reaction. The DPRK is seriously contemplating a measure to counter the US oft-repeated demand that it scrap its nuclear program first," he said.

WAR.WIRE