The purpose of Kim's trips to Guangzhou and Shenzhen seemed to be to study China's economic reforms and its high-tech industry. He left Shenzhen late Sunday aboard his armored train, headed for Beijing, the Hong Kong-based Wen Wei Po reported.
The fastest route by train takes about 24 hours.
Kim was to meet Chinese President Hu Jintao Tuesday, the South Korea-based Chosun Ilbo reported, citing sources in Beijing. The talks are likely to focus on dealing with U.S. sanctions against Pyongyang for alleged currency counterfeiting and weapons trafficking, and also on resuming the stalled six-party talks on North Korea's nuclear programs.
Since he entered China Tuesday Kim's itinerary has been the subject of intense foreign media speculation. A Japanese television station caught him on camera outside a hotel in Guangzhou, and unusual security arrangements there and in Shenzhen hinted at his activities.
Chinese authorities have not confirmed the visit, and a blackout has been imposed on Chinese media.
Media watchdog Reporters Without Borders blasted Chinese authorities for their lack of transparency, describing it as "an orchestrated state lie to protect the planet's worst dictator."