Beijing (CNN) -- Grainy photos of the reclusive North Korean leader in China appeared on local websites but the Chinese government Tuesday declined to confirm Kim Jong Il's visit to his nation's closest ally.
"We arrange visits by foreign leaders according to our usual practices and out of respect for visiting leaders," Foreign Ministry spokeswoman Jiang Yu said.
"To promote good neighborly and cooperative relations with DPRK is an unwavering policy of the Chinese Communist Party and the Chinese government," she said, referring to North Korea by its formal name of Democratic People's Republic of Korea, or DPRK.
China usually confirms North Korean officials' visits only after they have returned home.
South Korean media earlier reported that during a trilateral summit in Japan, Chinese Premier Wen Jiabao told South Korean President Lee Myung-bak Sunday that Kim was on a weeklong trip to China to study economic development.
Among the latest photos online are images allegedly showing Kim entering a supermarket and taking a boat tour Monday in the scenic eastern city of Yangzhou, some 300 kilometers (186 miles) from Shanghai. The leader checked out prices for rice and oil in the supermarket but did not make any purchases, according to South Korean news accounts.
South Korean and Japanese media, whose journalists usually doggedly follow the North Korean ruler on such trips, reported that Kim's special train crossed the border into China on Friday and the leader started his journey with several stops in the northeast, including a tour at one of the China's biggest automakers.
Kim's train then apparently traveled 3,000 kilometers (1,864 miles) south to Yangzhou, the hometown of former Chinese President Jiang Zemin, prompting speculations about a meeting between the two.
Kim is rumored to have visited solar power and electronics companies in Jiangsu province, where Yangzhou is located. He is believed to be traveling next to Shanghai or the southern metropolis of Guangzhou, before heading back north to Beijing for a summit with Chinese President Hu Jintao.
If confirmed, this would be Kim's third trip to China in a little over a year, signaling what many observers call his sense of urgency in strengthening economic ties with Beijing and seeking Chinese support for his succession plans. Earlier, rumors surfaced about the presence of Kim's youngest son and heir apparent, Kim Jong Un, in the delegation.
With heavy sanctions still in place on North Korea after its nuclear and missile tests, analysts say the communist nation clearly needs help, especially in light of recent reports that an unusually harsh weather has ruined its winter crop.
"Kim Jong Il wants to get something from South Korea or the U.S. or China -- economic aid or security assurances -- but at the moment he is not getting anything and China is preventing North Korea from further provocations," said Choi Jin-wook of Seoul's Korea Institute of National Unification. "Kim wants to know what China is going to do for them."
As a U.S. government delegation traveled Tuesday to North Korea for a four-day trip to assess the food situation, China remained largely quiet on how it would respond to its isolated neighbor's aid requests.
"Over the years China, within its means, has provided some assistance to DPRK aimed at helping it improve its people's livelihood and developing its economy," Foreign Ministry spokeswoman Jiang said. "We support international aid projects in the DPRK."
Journalist Andrew Salmon contributed to this report.