BEIJING, Dec. 6 (Xinhua) -- China has maintained communication with the Republic of Korea (ROK) on the East China Sea air defense identification zone (ADIZ), Chinese Foreign Ministry spokesman Hong Lei said Friday.

"We are ready to maintain communication with the ROK side under the condition of equality and mutual respect," Hong said at a regular press briefing.

When asked to comment on ROK's attempt to expand its air defense identification zone, Hong said the ROK's move should be in line with its national laws and international norms.

Hong said an ADIZ is not part of a country's territorial airspace and has nothing to do with the administrative rights over sea and airspace. It is established for identification and early warning.

Official sources said the ROK is considering expanding its ADIZ to cover a number of submerged rocks within the exclusive economic zone of China, which partially overlaps that of the ROK.

China announced its ADIZ over the East China Sea on Nov. 23. The ROK's ADIZ was set up by the U.S. air force in 1951.