Kim spent Thursday in the provincial capital of Guangzhou, the South China Morning Post reported, describing a convoy of limousines, minibuses and police cars that arrived at the city's luxury White Swan Hotel after all guests were ordered to leave.
A hotel spokesman said the hotel's 843 rooms and all its dining establishments had been reserved until Monday.
Foreign media have given conflicting reports as to Kim's whereabouts since his private armored train entered China early Tuesday. The most likely scenario had him traveling to Shanghai, then on to the southern cities of Guangzhou and Shenzhen.
China has long tried to encourage North Korea to copy its economic reforms, as the country has become increasingly reliant on China for food and energy.
Kim is likely to stop in Beijing for talks with President Hu Jintao before returning home. His agenda is thought to include asking China to pressure the United States to lift sanctions on North Korean companies.
Chinese media have not mentioned the trip. The last time Kim visited China, in April 2004, the visit was not reported until after he returned to Pyongyang.