BEIJING - Chinese marine surveillance ships continued their regular patrols in territorial waters of the Diaoyu Islands on Thursday, the State Oceanic Administration (SOA) said.

The fleet on duty for the patrols on Thursday consisted of three ships, Haijian 49, Haijian 51 and Haijian 5001, according to the SOA.

China has strengthened patrol and law enforcement in waters surrounding the Diaoyu Islands since September 14, 2012, after the Chinese government announced the base points and baselines of the territorial waters of the Diaoyu Islands and their affiliated islets.