A Foreign Ministry spokesman said Wednesday that the recent patrol conducted by marine surveillance vessels in waters near the Diaoyu Islands constitutes a "normal activity" intended to exercise China's jurisdiction over the islands.

"The marine surveillance fleet is conducting regular patrols and law enforcement in waters around the Diaoyu Islands, which are China's territory. This is well-grounded," spokesman Hong Lei said at a regular press briefing.

Hong's remarks referred to the expelling of several Japanese vessels that were found illegally sailing around the islands Tuesday morning.

According to a statement issued by the State Oceanic Administration, a fleet of four marine surveillance ships encountered the Japanese vessels at 10 a.m. on a routine patrol. They conducted surveillance on the Japanese vessels and took photographic evidence of their presence.

The fleet also radioed the Japanese vessels to reiterate China's sovereignty over the Diaoyu Islands and the waters around them.