"As North Korea's neighbour, China is seriously concerned about the emergence of new, complex elements in the peace and stability of the Korean peninsula situation," said Foreign Minister Li Zhaoxing.

"This is caused by many reasons. Among them, there has been long-term enmity between some major parties and it has led to serious mistrust," he said.

The comments, made at a meeting of Southeast Asian ministers together with their counterparts from China, Japan and South Korea, were relayed to the media by China's foreign ministry spokeswoman, Jiang Yu.

China and South Korea are making a joint push for North Korea to come back to six-nation talks on its nuclear ambitions, which it has boycotted since November over US financial sanctions.

"To narrow differences and to promote mutual trust, China has always made efforts to push forward the six-party progress through this platform to increase understanding and eliminate obstacles through dialogue, for the peaceful resolution of the problem," Li said.

"The current situation is still serious. China as usual will be willing to play a constructive role and hopes all sides can exercise restraint, keep calm and to do more things which are conducive towards the resumption of six-party talks and to prevent the situation from getting worse."

His comments were the strongest since arriving in the Malaysian capital for the ASEAN Regional Forum security dialogue which will be held on Friday, bringing together all the participants in the six-way talks.

China has tentatively scheduled an informal session between the six countries' foreign ministers -- China, Japan, the two Koreas, the United States and Russia -- for Friday afternoon.

But US envoy Christopher Hill said Wednesday that North Korea had given no sign that it was willing to rejoin the talks.