Close aides of Kim Jong-un, the 26-year-old third son and heir apparent of North Korean leader Kim Jong-il, last week attempted to assassinate the leader's first son Jong-nam, KBS reported Monday citing Chinese government sources.

Aides to Kim Jong-un planned to assassinate Jong-nam, who lives in Macau, after first eliminating his close aides in North Korea. The sources said, "It seems they tried to assassinate Kim Jong-nam without telling Kim Jong-il."

The plan was foiled when the Chinese government found out about it early last week. "The Chinese government warned North Korea to stop the assassination attempt, and sent intelligence and military officers to Macau and spirited Kim Jong-nam to a safe place," the sources said.

In protest against North Korea's nuclear test and the assassination plan, China reportedly shelved all collaboration projects with North Korea such as developing natural resources and building infrastructure, part of projects celebrating the "China-North Korea Friendship Year." The sources said China also delivered a message that it would halt food and fuel assistance if North Korea continues its provocations.

The sources said the reason China was protecting Kim Jong-nam is because he has been developing friendships with high-ranking Chinese officials for a long time. KBS said Kim Jong-nam is likely to weigh option of seeking asylum in China.