China expressed concern about the possible deployment of an advanced US missile defense system in South Korea during talks Wednesday between their defense chiefs.

China expressed concern about the possible deployment of an advanced US missile defense system in South Korea during talks Wednesday between their defense chiefs, Seoul military officials said.

Washington is considering whether to install the politically sensitive THAAD (Terminal High-Altitude Area Defence) system in the South, a close US ally which hosts 29,000 American troops.

US officials have tried to portray any THAAD system based in South Korea as non threatening. It is designed to shoot down ballistic missiles at a higher altitude with a "hit-to-kill" approach.

At talks in Seoul with his South Korean counterpart Han Min-Koo, Chinese defense minister Chang Wanquan expressed "concern" at the US move, Han's office said.

It was the first time that a ranking Chinese official had publicly raised the THAAD issue with South Korea, according to Yonhap news agency.

The ministers agreed to establish a hotline between them as soon as possible, Yonhap said, adding related talks would probably begin next week.

China, despite being North Korea's sole major ally, has gradually strengthened military cooperation and exchanges with South Korea.