SEOUL - South Korea on Sunday announced a southward expansion of its air defense identification zone (KADIZ), encompassing submerged rocks within the overlapping exclusive economic zones (EEZ) of China and South Korea.

"The Republic of Korea (ROK) government decided to change the KADIZ range after considering the specialty of air military operations, the flight information region (FIR) range under the aviation law and international practices," Defense Ministry spokesman Kim Min-seok said at an emergency press briefing.

The ministry said the new zone included the nation's two southernmost islands of Marado and Hongdo as well as the Suyan Rock, a submerged reef within the overlapping EEZ of China and South Korea.

The ministry said its eastern and western boundaries remained the same as before, adding the new zone would take effect from December 15.

It marked the first change in more than six decades to the KADIZ, which was drawn in 1951 by the US Air Force during the 1950-53 Korean War.

The spokesman said the new KADIZ would not restrict flights by international civilian airliners or encroach on territorial air and interests of neighboring countries.

He said the South Korean government had provided sufficient explanations about the expansion to neighboring countries through defense and diplomacy channels ahead of the announcement.

"I don't think the relations between South Korea and China will deteriorate seriously because of this," Yonghap news agency quoted a South Korean official as saying. But the official, who requested anonymity admitted reactions from the United States, China and Japan varied.

On ROK's attempt to expand its air defense identification zone, Chinese Foreign Ministry spokesman Hong Lei told a regular media briefing Friday that the move should be in line with its national laws and international norms.

Hong said an ADIZ was not part of a country's territorial airspace and had nothing to do with the administrative rights over sea and airspace.

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

During a meeting with visiting US Vice President Joseph Biden on Friday, South Korean President Park Geun-hye explained South Korea's stance on the KADIZ issue, to which Biden responded vaguely, saying he "appreciated President Park's explanation and South Korea's efforts".

South Korea finalized its position on the expansion right after the meeting.