Japan is keeping a close watch on the Chinese navy's activities in waters around the nation after fighter jets and helicopters were seen taking off from and landing on a Chinese aircraft carrier off Okinawa Prefecture, the government's top spokesman said Monday.

The activities could be part of China's efforts to bolster its joint aerial and maritime operational capabilities in the Pacific, and Japan will continue to take heed of the situation and keep up surveillance at sea and in the air, Chief Cabinet Secretary Hirokazu Matsuno told a briefing.

The Chinese navy's flotilla, which includes the aircraft carrier Liaoning, missile destroyers and a supply ship, sailed through waters between the prefecture's main island of Okinawa and Miyako Island last week. Japan's Maritime Self-Defense Force dispatched its Izumo helicopter carrier there for surveillance.