North Korean leader Kim Jong-il left Beijing Thursday on a heavily guarded train, after two days of talks with Chinese leaders during which he is thought to have asked for increased aid for his country’s beleaguered economy.

Since he arrived in China last week, Mr. Kim has visited factories, a solar panel plant, and a supermarket, according to Japanese and South Korean media reports, in an apparent effort by Beijing to persuade him to undertake economic reforms.

“There has been a clear emphasis on economic development throughout the trip,” says John Delury, who teaches International Relations at Yonsei University in Seoul. “It has highlighted China as an economic development model for North Korea.”

Kim’s presence in China has not been officially confirmed by either the Chinese or North Korean governments, as has been standard on previous trips, which were acknowledged only after they ended. This was his third trip to his biggest benefactor in just over a year.

The visit coincided with a fact-finding trip to Pyongyang by a US delegation led by Washington’s special envoy for North Korean human rights, Robert King. The purpose was to assess the food situation in the reclusive nation, which has been appealing internationally for emergency food aid.

The United Nations warned in March that the North Korean government food distribution system risked running dry by this month, putting a quarter of the country’s 24 million people at risk of starvation.

The US suspended food aid to North Korea two years ago amid fears the donations were going to the military rather than to hungry citizens, but former US president Jimmy Carter appealed for a resumption of the assistance after a recent trip to Pyongyang.

China, which sees North Korea as a useful buffer against the United States and its regional allies, has kept Kim Jong-il’s regime afloat with economic assistance as other sources have dried up in anger at Pyongyang’s behavior, especially its two nuclear weapons tests which drew UN sanctions.

But Beijing is also thought to be keen to encourage its protégé to adopt the sort of economic policies that have enriched China over the past 30 years. Chinese premier Wen Jiabao told South Korean president Le Myung-bak over the weekend that Kim was studying “economic development” during his visit.

The Chinese authorities have given the North Korean leader other opportunities in the past for such study, but they have not yet led to any signs of significant economic reforms.

“There is no guarantee of anything,” cautions Professor Delury. “These kinds of trips have happened before and not much has changed. But this is a signal that there is interest at the top level in North Korea in maybe giving another push” to reforms.

South Korean Foreign Ministry spokesman Cho Byung-jae told reporters in Seoul Thursday that his government hoped Kim would learn lessons in China that would “speed up opening of North Korea’s economy, improving the lives of North Koreans,” Reuters reported.