China is lobbying neighbours to sign up to a road map for renewed nuclear disarmament talks with North Korea, whose leader Kim Jong-il is visiting China amid conciliatory words and threats of "holy war". The details of Beijing's plan for restarting stalled six-party nuclear talks came from a South Korean diplomatic source, who spoke on Saturday after discussion in Seoul with Wu Dawei, China's top envoy in the talks, according to Reuters. But the source, as well as a Japanese official speaking in Beijing, stressed that big obstacles remained, even if the secretive Kim's trip to China yields another vow of North Korea's willingness to sit down and discuss a dormant deal to scrap its nuclear weapons in return for aid. "We don't want to restart six-party talks for the sake of talks," the South Korean diplomatic source said. "North Korea should change its attitude and show seriousness in denuclearising." China's regional lobbying, and courting of the reclusive Kim, highlight the pressures that North Korea -- isolated, poor and with a brace of primitive nuclear bombs -- has brought to bear on northeast Asia, home to the world's second and third biggest economies and a big U.S. military presence. Kim, 68, and his son and heir apparent, Kim Jong-un, were in China to visit the school of senior Kim's father and founder of North Korea, Kim Il-sung, a source with knowledge of the secretive trip told Reuters. "Trust me, it's 100 percent both are here," the source said, declining to give details when asked. Kim Il-sung attended the Yu Wen High School in the northeastern Chinese city of Jilin in the 1920s. The school houses a memorial hall to Kim which is not open to the public. The museum was renovated recently ahead of a visit by a group of North Korean dignitaries, a second source said.