Evan Medeiros, a senior director for Asian affairs at the U.S. National Security Council (NSC), made an unofficial visit to South Korea recently to discuss China's air defense identification zone (ADIZ) issue with Seoul government officials, the Yonhap News Agency reported on Thursday.

"South Korea and the U.S. are consulting (on the issue) both in Seoul and Washington. There were consultations with the senior aide Medeiros who visited Seoul recently," Yonhap quoted a senior government official as saying.

The senior White House official unofficially met with Seoul officials from the presidential office Cheong Wa Dae to explain the U.S. stance on the Chinese ADIZ, while exchanging views over the issue.

After completing his visit in Seoul, Medeiros flew to Japan to discuss the ADIZ issue, the report said.

Regarding the report, Seoul's Foreign Ministry spokesman Cho Tai-young said at a regular press briefing that the U.S. official visited South Korea on Wednesday to discuss preparations for the planned visit by U.S. Vice President Joe Biden.

Biden was scheduled to travel to three Asian powers, including China, Japan and South Korea, next week.

The spokesman said that Medeiros met with Seoul's vice foreign minister and other presidential officials during his trip to Seoul, noting that his visit focused on preparations for Biden's upcoming visit.

His comments came after China announced last week the ADIZ over the East China Sea that partly overlaps with Seoul's military air zone, or KADIZ, and covers the Ieodo, a southernmost submerged rock claimed by Seoul.

The newly launched ADIZ of China and the existing KADIZ has overlapping areas of 20 km wide and 115 km long.

Senior military officials from South Korea and China held the third bilateral strategic talks in Seoul on Thursday to discuss the ADIZ issue.