BEIJING, Oct. 2 (Xinhua) -- Four Chinese marine surveillance ships patrolled in the waters off the Diaoyu Islands on Tuesday after the Japanese right-winger's intrusion, the Foreign Ministry confirmed.

China is strongly dissatisfied with and firmly opposes the Japanese right-wingers' illegal entrance into the waters off the Diaoyu Islands and is keeping high vigilance to their intention and purpose, FM spokesman Hong Lei said Tuesday at a regular press briefing.

The provocation of this kind will make the situation more complicated if not stopped, said Hong Lei.

The patrol team -- composed of Haijian 50, Haijian 15, Haijian 26 and Haijian 27 -- are carrying out normal rights-safeguarding activities around the Diaoyu Islands, according to a statement from the State Oceanic Administration.