Japan's Defense Ministry says a Chinese naval ship sailed inside Japan's territorial waters off the southern prefecture of Kagoshima on Sunday morning.

Defense officials say the survey ship was first spotted traveling northward in Japan's contiguous zone south of the island of Yakushima around 12:50 a.m.

Officials say it entered Japan's territorial waters southwest of the island at around 2:30 a.m. and left the territorial waters around 4:10 a.m., heading west.

The officials say this is the first time this year that Chinese government ships have been sighted in Japan's territorial waters off the island of Yakushima. They say the Japanese government used diplomatic channels to convey its concerns to China.

Chinese naval vessels last year navigated inside Japan's territorial waters around the island five times.

The Defense Ministry is monitoring the activities of Chinese vessels and is analyzing the purpose of their navigations.