Reports indicate Kim Kye-gwan had a friendly discussion with China's Wu Dawei in Pyongyang Tuesday, prompting speculation the two sides are trying to restart six-party negotiations that stalled in late 2008, South Korea's Yonhap news agency reported.
Last week a senior Chinese military official said he sees a chance to resume nuclear talks with North Korea, citing signs that tensions on the Korean Peninsula are easing.
North Korea has made overtures about four-party talks to both South Korea and Washington.
Choe Ryong-hae, the vice marshal of the North Korean People's Army, proposed "four-party talks" to China in May when he visited Beijing.
"Such talks are unlikely because there is no pledge from Pyongyang to take sincere steps toward denuclearization," a diplomatic source told Yonhap.
The source added: "The U.S. won't agree to hold such talks unless North Korea meets preconditions."