Four Chinese patrol ships intruded into Japan's territorial waters off the Senkaku Islands in the East China Sea on Saturday. 
The Japan Coast Guard said that the Chinese vessels entered waters off Uotsuri Island, one of the Senkakus, Japan's broadcaster (NHK World) reported. 
The ships stayed in the waters for more than an hour and a half before moving to the contiguous zone just outside the territorial waters. 
The four vessels first entered the zone on Thursday, shortly after four others left. 
It's the fifth day this year that Chinese ships have entered Japanese waters off the Senkaku Islands. The last time was on February 6th. 
Japan controls the islands. The government maintains they are an inherent part of Japan's territory. China and Taiwan claim them.

Source: QNA