Beijing: South Korea has declared it will expand its air defence zone in a direct response to a similar zone announced by China that has sharply increased regional tensions.

Seoul’s Defence Ministry said on Sunday its new zone, which will start on December 15, will cover a submerged rock reef in waters off its south coast known internationally as Socotra Rock, but which South Korea calls Ieodo, and China calls Suyan.

The disputed islands in the East China Sea known as the Diaoyu by China and the Senkaku by Japan. Credit:AP

The move is aimed at bolstering South Korea’s sovereignty over the reef and other islands around the Korean Peninsula, and has been made in response to China’s contentiously announcing an air defence identification zone on November 23 that covered the area and overlapped an existing air defence zone established by Japan.

On Sunday, The move comes as three Chinese coastguard ships sailed through the disputed waters off Tokyo-controlled islands in the East China Sea on Sunday – the first time Chinese ships had entered the waters since declaring its new air defence zone.