A group of Chinese diplomats in charge of Korean affairs visited North Korea last week, marking the first visit by Chinese officials since the high-profile purge of leader Kim Jong-un's uncle about two months ago, a diplomatic source said Wednesday.

The Chinese delegation, led by Deputy Director-General of Asian Affairs Xing Haiming, included some diplomats who are working to persuade North Korea to return to the long-stalled multilateral talks aimed at ending the North's nuclear weapons development, the source said on condition of anonymity.

"To my knowledge, the Chinese delegation included working-level officials in charge of the six-party talks," the source said.

Although the purpose of the visit by the Chinese delegation remains unclear, it signals that Beijing and Pyongyang have resumed their regular diplomatic exchanges since the Dec. 13 execution of Jang Song-thaek, the once-powerful uncle of Kim.

Jang's dramatic downfall marked the biggest political upheaval since the North's young leader Kim took power after his father's death in late 2011.

China, North Korea's key ally and economic lifeline, has been in a delicate position because Jang was considered a supporter of China-style reforms to revive the North's moribund economy and played an important role in dealing with economic projects with Beijing.

Last week's visit by Chinese diplomats to North Korea came days after Washington's top nuclear envoy, Glyn Davies, visited Beijing and held talks with his Chinese counterpart, Wu Dawei, on ways to resume the six-party talks.

Since its third nuclear test in February last year, North Korea has repeatedly expressed its willingness to reopen the six-party talks "without preconditions," but Seoul and Washington have demand Pyongyang demonstrate its sincerity first by taking steps toward denuclearization.

China has been more accommodating toward North Korea, urging South Korea and the U.S. to lower their bar for sitting down at the negotiating table.

The six-party talks, which involve the two Koreas, the U.S., China, Russia and Japan, have been dormant since late 2008. (Yonhap)