BEIJING -- China on Wednesday denied its island building in the South China Sea would "militarize" the area, after US and Australian defense and foreign ministers expressed concern during their annual meeting.

"China's construction on the Nansha Islands serves mostly civilian purposes, helping deliver our international responsibilities and obligations and providing more public good," Foreign Ministry spokesperson Hua Chunying told a regular news briefing.

The lighthouses on Huayang and Chigua reefs went into operation on Oct 10 and have significantly improved navigation safety in the South China Sea.

"Some countries flex their military muscles and hold frequent large-scale drills with their allies in the South China Sea, which is the most important factor militarizing the waters. China expresses serious concern over this," she said.

China's military deployment is "necessary, limited and defense-oriented," Hua said.