BEIJING, Aug. 8 (Xinhua) -- The Chinese Foreign Ministry confirmed on Thursday that a fleet of ships from the China Coast Guard (CCG) recently patrolled the country's territorial waters surrounding the Diaoyu Islands.

"The Diaoyu Island and their affiliated islets are an integral part of Chinese territory and have been since ancient times," foreign ministry spokesman Hong Lei said, adding that the patrols are designed to exercise China's inherent sovereignty.

Hong said the Japanese side should face up to history and reality, stop all provocative words and deeds, and make substantial efforts to appropriately manage and resolve tensions over the sovereignty of the Diaoyu Islands.

The spokesman also said that as the CCG fleet patrolled the waters, they spotted a Japanese vessel, believed to belong to a right-wing Japanese politician, illegally sailing there.

Hong said the Chinese Foreign Ministry and the Chinese embassy in Tokyo have respectively lodged solemn representations and expressed strong protests to the Japanese side.

The Japanese vessel has already left the Chinese territorial waters, he added.

The CCG, which merges China's maritime law enforcement functions of four agencies responsible for fisheries administration, maritime surveillance, customs enforcement and border control, formally unveiled its board last month.