North Korean leader Kim Jong-il reportedly arrived in Beijing Wednesday after touring industrial facilities in eastern China, but neither country would confirm the visit.
The ruler's armored train was seen in Beijing and a motorcade under unusually tight security later swept through central Beijing's Chang'an Avenue, suggesting the visit has begun, Reuters reports.
Kim is suspected of being afraid of flying and travels by his personal train.
The reclusive ruler of impoverished North Korea is expected to have a summit meeting with Chinese President Hu Jintao, the leader of Asia's biggest economy, according to South Korean reports.
The Chinese government has refused to confirm the visit, but grainy photographs of Kim appeared on local websites Tuesday, CNN reports.
The images allegedly show the leader entering a supermarket to inspect prices and taking a boat tour.
"We arrange visits by foreign leaders according to our usual practices and out of respect for visiting leaders," Foreign Ministry spokeswoman Jiang Yu told CNN.
"To promote good neighborly and cooperative relations with DPRK [Democratic People's Republic of Korea] is an unwavering policy of the Chinese Communist Party and the Chinese government."
If confirmed, this would be the third visit by Kim to China in just over a year.
Analysts watching the trip say North Korea has suffered greatly under sanctions and a harsh winter, and the country needs help dealing with its food shortage.
The tour is believed to be aimed at studying China's economic boom, and Kim reportedly visited manufacturing sites in northeastern and eastern China before arriving in the capital, AFP reports.
As Kim visited China, a U.S. government team visited North Korea to assess its requests for food aid.