Japan would strengthen surveillance and gather necessary information, chief cabinet secretary Yoshimasa Hayashi told a regular press briefing in Tokyo.

Japan has also sent “an appropriate message” to China, Hayashi said without elaborating.

Iwo Jima is located 1,000km south of Tokyo.

A statement by Japan’s joint staff over the weekend said that the Liaoning, accompanied by some other ships, sailed in the sea within Japan’s exclusive economic zone near Minamitorishima, a remote island east of Iwo Jima.

Japan also confirmed fighter jets and helicopters taking off and landing from Liaoning in the waters southeast of Iwo Jima yesterday.

China’s foreign ministry today defended the aircraft carrier’s voyage as “fully in line with international law and practice”.

Ministry spokesman Lin Jian told a regular press briefing that China had “always pursued a defensive national defence policy” and urged Japan to look at the issue “objectively and rationally”.