The China Coast Guard (CCG) said on Saturday that it has taken necessary control measures and warned off a Japanese fishing vessel and several patrol ships that illegally entered China's territorial waters near the Diaoyu Dao earlier in the day.

The Diaoyu Dao and its affiliated islands are China's inherent territory, and the CCG conducted maritime rights protection and law enforcement activities in waters under China's jurisdiction in accordance with the law, said Gan Yu, spokesperson for the CCG, in a statement.

"We urge the Japanese side to immediately stop all illegal activities in the waters and make sure incidents like this will never happen again," the spokesperson said.