A train carrying the reclusive Kim left Pyongyang and entered Chinese territory via the North Korean border city of Shinunju late Sunday, the Yonhap news agency said quoting diplomatic sources.

Kim is expected to arrive in Beijing on Tuesday or Wednesday for talks with Chinese leaders, including President Hu Jintao, Yonhap said, without elaborating on concrete schedules.

Earlier, Seoul's state-run broadcaster KBS also quoted unnamed Chinese diplomatic sources as reporting that Kim and 40 other officials would visit China from Monday through Thursday.

Officials in Beijing and Seoul could not confirm the visit.

Kim will meet with President Hu, Premier Wen Jiabao, ex-President Jiang Zemin and other top Chinese officials on the third round of six-nation talks aimed at easing a standoff over North Korea's nuclear ambitions, KBS said.

KBS said Kim's "special train" made a brief stop at the Chinese border city of Dandong to receive greetings from Chinese officials amid heavy security.

Chinese officials have recently said Beijing is working to step up exchanges with Pyongyang, including an increase in high-level visits that could include a trip by North Korea's Kim.

Chinese Foreign Minister Li Zhaoxing visited Pyongyang last month.

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

China has been hosting the six-nation nuclear talks which also bring together the two Koreas, the United States, Russia and Japan. New talks are to open in Beijing by June.

No breakthrough was made in the nuclear standoff in the first two rounds of Beijing talks due to differences over a US demand for the complete dismantling of Pyongyang's nuclear programs.

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

Pyongyang denies having a uranium program and has said it will freeze its plutonium weapons program in return for simultaneous rewards from Washington.

The six nations involved in the talks have agreed to establish a working group to narrow the differences and prepare for the next round of negotiations.

WAR.WIRE