North Korean leader Kim Jong-un's rule is unlikely to collapse as he has firm control over the country's military and the ruling party, a former top Chinese diplomat was quoted as saying Saturday.

Former Chinese State Councilor Tang Jiaxuan made the remark during a breakfast meeting with members of the Korea-China Exchange Association, participants said.

Tang, an expert on Korean Peninsula issues, said that late North Korean leader Kim Jong-il, father of the current leader, had laid all the groundwork before his death for his son to smoothly take over, according to participants.

Tang, who served as China's foreign minister from 1998-2003, was in Seoul as part of a five-day trip that began on Wednesday.

Tang also said that Chinese President Xi Jinping made clear during a meeting with a special envoy of the North's leader last month that North Korea's nuclear weapons are unacceptable, according to the participants.

China is Pyongyang's No. 1 ally and a key provider of economic aid and diplomatic protection.

In recent months, however, China has apparently been taking a tougher approach to Pyongyang, especially after the North's long-range rocket launch in December and its third nuclear test in February. 

Beijing has since backed a U.N. sanctions resolution against the North and has been carrying out the restrictions more vigorously than before. (Yonhap News)