TOKYO: A Chinese naval intelligence ship briefly entered Japan's territorial waters early Wednesday morning, a Japanese government spokesman said.

Deputy Chief Cabinet Secretary Hiroshige Seko said a Maritime Self-Defense Force plane spotted the ship in Japanese waters west of Kuchinoerabu island in southern Japan before dawn. The ship sailed out of Japan's waters about 90 minutes later, he said.

Japanese public broadcaster NHK reported it was the first time a Chinese naval vessel had been spotted in Japan's waters since a submarine was detected off Ishigaki island in 2004.

Following the latest incident, a Foreign Ministry official expressed concern to a Chinese embassy official in Tokyo about Chinese naval activity generally, Seko said. Japan reacted more harshly last week after a Chinese navy ship sailed near the Senkaku islands, which China also claims and calls the Diaoyu islands.