China announced on Saturday that it was setting up the zone in the East China Sea, incorporating islands disputed by China, Japan and South Korea.
Seoul called the move “regrettable” as it overlapped with its own air defense zone and incorporated a disputed, submerged, South Korean-controlled rock – known as Ieodo – that has long been a source of diplomatic tension with Beijing.
“I’d like to say once again that we have unchanging territorial control over Ieodo,” South Korean defence ministry spokesman Kim Min-Seok told reporters on Monday.
Kim said the two sides would have “in-depth discussions” on the matter during scheduled talks between their deputy defence ministers in Seoul on Thursday.
In an effort to strengthen its claim over Ieodo, South Korea built a maritime research station on the submerged rock in 2003 — despite strong Chinese opposition.
China’s declaration of the new “air defence identification zone” triggered an angrier response from Japan, which refused to recognise the measure and warned of “unpredictable events” if Beijing should seek to have it enforced.
China has already released a set of aircraft identification rules that must be followed by planes entering the area.
The development further raises the stakes in an already dangerous stand-off between Tokyo and Beijing over a set of islands, known as the Senkakus in Japan and the Diaoyus in China.
The dispute has seen coastguard vessels and planes from both sides engage in tit-for-tat shows of force.