BEIJING - A four-ship fleet from the China Coast Guard (CCG) patrolled the country's territorial waters surrounding the Diaoyu Islands on Wednesday, the State Oceanic Administration said.

Comprising CCG ships 2350, 1126, 2102 and 2166, the fleet spotted Japanese ships sailing there and "sternly" declared China's sovereignty over the Diaoyu Islands, the administration said in a brief statement.

The Japanese ships were told to immediately leave China's territorial waters.

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