Japan's Defense Ministry says the Chinese aircraft carrier Shandong is sailing toward the South China Sea after navigating in the Pacific Ocean south of Japan.

Ministry officials said on Monday that the Maritime Self-Defense Force spotted six Chinese naval vessels, including the Shandong, traveling in the Pacific, about 580 kilometers south of Okinawa's Miyakojima Island, on Sunday.

The officials said the Chinese vessels were crossing the Bashi Channel between Taiwan and the Philippines and traveling toward the South China Sea on Monday.

They said the aircraft carrier had been sailing in the Pacific for nine days through Sunday. They also confirmed that fighter jets and helicopters carried out takeoff and landing maneuvers about 570 times.

The Shandong is China's first domestically built carrier and was commissioned in December 2019.

Japanese officials say they believe China is trying to improve the capabilities of its carriers.

The officials say they will maintain vigilance and closely monitor the situation.