North Korean leader Kim Jong Il arrived in Beijing on Wednesday, raising speculation that he could meet Chinese President Hu Jintao, South Korea's Yonhap news agency reported.
Kim entered Beijing's Diaoyutai State Guesthouse shortly after his special train arrived in the Chinese capital following an overnight journey from the eastern city of Nanjing, the agency said.
Kim crossed the border into north-eastern China by train on Friday and has visited at least four other cities in the last six days, dpa reported.
Previous visits by Kim were not confirmed by the Chinese or North Korean governments, or their state media, until after they had concluded.
Footage posted on the popular Chinese video-sharing website Youku appeared to show Kim arriving at an electronics plant in Nanjing on Tuesday.
Kim had dinner with former Chinese president Jiang Zemin and other officials in nearby Yangzhou on Monday, Yonhap quoted unidentified sources as saying.
China's Global Times newspaper on Tuesday quoted "sources close to the local government" in Yangzhou as saying officials including the city's Communist Party secretary met Kim as he arrived by train late Sunday.
Kim Jong Un, Kim Jong Il's son and apparent successor, was not part of the North Korean delegation in Yangzhou, the newspaper quoted the local government sources as saying.
Speaking after a trilateral summit in Tokyo on Sunday, South Korean President Lee Myung Bak quoted Chinese Premier Wen Jiabao as saying during the summit that Kim's visit to China was designed to help North Korea to learn about economic development and to assist the revival of the Stalinist state's economy.
Robert King, the US envoy for North Korean human rights, arrived in Pyongyang on Tuesday for a five-day visit to evaluate the government's January request for food aid.
The United Nations estimates about 6 million North Koreans, or a quarter of its population, need urgent food assistance.