China has called on the countries involved in the Korean Peninsula nuclear talks, especially the "principal parties", to demonstrate sincerity and flexibility in promoting the six-party talks.

Chinese Foreign Ministry spokesman Qin Gang said on Tuesday the talks have encountered "new" and "complicated" problems.

China has always played a "positive" and "constructive" role in promoting the six-party talks, Qin said. China advocates the denuclearization of the Korean Peninsula, and proposes to settle the nuclear issue through negotiations, which will not only benefit peace and stability of the Korean Peninsula and Northeast Asia, but is also in the interests of relevant parties, he said.

"The Chinese side has been in close contact with parties concerned in a bid to promote progress," the spokesman said. Other parties concerned have also expressed their appreciation for China's role in this field.

"China will continue to make its due contribution in promoting the six-party talks and denuclearization of the Korean Peninsula," he said.

The six parties include China, the Democratic People's Republic of Korea, the United States, the Republic of Korea, Russia and Japan.