Kim Jong Il in surprise visit to China

North Korean leader Kim Jong Il was in China today on a visit to a school - his second appearance in the country this year.

The visit, which has not been announced by either country, is highly unusual, coming just three months after Kim's last appearance in China.

The move came as a surprise because former US president Jimmy Carter is in North Korea and many had speculated the two would meet.

But Kim's stop in Jilin city in north-eastern China was confirmed by two teachers at the Yuwen Middle School, which Kim's father, the late president Kim Il Sung, once attended.

"He definitely came over. But I'm not sure if his son was with him or what time he came," said a physical education teacher.

Another teacher said Kim visited the school in the morning for about 20 minutes.

Kim may be travelling with a son to consult with Chinese officials on plans to transfer power to a successor, South Korea's Yonhap News Agency and YTN television in Seoul said.

It is widely believed that Kim is preparing to transfer power to his third and youngest son, Kim Jong Un, and many North Korea watchers believe the son will be granted a key party position next month.

Kim Il Sung attended the school from 1927 to 1930 after his family fled the Japanese occupation of Korea.

At the time, Yuwen was a hot-bed of leftist thinking. Biographies of Kim say that he began absorbing communist ideology while at Yuwen.

In 1928, Kim organised protests against "reactionary teachers" at Yuwen in addition to demonstrations against Japan and the purchase of Japanese goods, according to the Jilin provincial government's website.

China's continued support is crucial for pressing issues on Kim's agenda and are likely to dominate the Workers Party meeting in September.

At this gathering, Kim's son is expected to be anointed as his successor, and steps will be outlined to revitalise the economy.

Kim last visited China in May, meeting top leaders, including President Hu Jintao. It is not known who he will meet on this trip, although someone of his stature would likely meet a senior leader.

The Tokyo Shimbun reported that Chinese Vice President Xi Jinping was travelling to Jilin to meet Kim.