BEIJING, Jan. 21 (Xinhua) -- A Chinese marine surveillance fleet continued patrolling China's territorial waters around the Diaoyu Islands on Monday and monitored Japanese ships that violated China's territorial waters.

The vessels -- Haijian 137, Haijian 23 and Haijian 46 -- followed and engaged in surveillance of the Japanese ships, solemnly declared China's sovereignty over the islands and demanded the Japanese ships' immediate departure from Chinese waters, according to a statement issued by the State Oceanic Administration.