Japan on Wednesday accused China of sending ships into its territorial waters around a chain of disputed islands.
Officials from the Japan Coast Guard said three Chinese Coast Guard ships entered the country’s territorial waters near the Senkaku Islands in the East China Sea.
Tokyo said it marked the 27th time this year that Chinese ships have been spotted entering Japanese territorial waters off the islands.
Deputy Chief Cabinet Secretary Yoshihiko Isozaki termed the alleged intrusion a violation of international law and called it "extremely regrettable and totally unacceptable," according to Kyodo News Agency.
Tokyo also lodged a protest with Beijing over the violation of international law, Yoshihiko told reporters.
The Japan Coast Guard claimed that it spotted Chinese ships near the islets in the East China Sea over the past two weeks.
On Tuesday, Japan's Defense Ministry said seven Chinese and Russian naval ships sailed near the Izu Islands south of Tokyo in the Pacific Ocean which they believed to be part of a joint patrol, according to the agency.
Beijing and Tokyo are locked in a dispute over the Japanese-controlled Senkaku Islands, which Beijing claims and calls the Diaoyu Islands.