China's vice foreign minister will fly to Seoul late Thursday after his visit to North Korea, in a rare back-to-back trip by a ranking Chinese official to both Koreas, officials said.

Liu Zhenmin has been visiting North Korea since Monday for meetings with officials there over security issues, including the North's nuclear weapons program.

The Chinese official will leave Pyongyang and fly straight to Seoul via Beijing Thursday evening for a three-day stay, according to the Ministry of Foreign Affairs.

Liu is scheduled to hold talks with his South Korean counterpart, Lee Kyung-soo, on Friday as well as Foreign Minister Yun Byung-se and other national security-related officials.

In his meetings with South Korean officials, Liu is expected to delve into the recent developments in the inter-Korean ties.

"(Liu's back-to-back visits to both Koreas) means China is playing a role by going between the countries," a South Korean government official said.

Liu became the most senior Chinese official to visit North Korea since the high-profile execution of leader Kim Jong-un's once-powerful uncle Jang Song-thaek in mid-December.

His visit will also be followed closely in Seoul as he is expected to relay any message from Pyongyang regarding the North's nuclear issues or inter-Korean relations. 

After months of negotiations, South and North Korea were to hold Thursday inter-Korean reunions of families separated by the 1950-53 Korean War, their first reunion event since the last one held in late 2010. 

The two countries also held high-level talks last week, raising hopes for a level of rapprochement.   (Yonhap)