Three Chinese government ships moved into territorial waters off disputed Tokyo-controlled islands late Monday, Japan’s coastguard said.
The maritime surveillance ships entered the 12-nautical-mile zone off Uotsurijima, one of the Senkaku islands which China claims and calls the Diaoyus, after 7:00 pm (1000 GMT), the Japan Coast Guard said in a statement.
The vessels remained in the waters for some two hours before leaving shortly after 9:00 pm (1200 GMT).
State-owned Chinese ships have frequently spent time around the five disputed islands in the East China Sea since Japan nationalised three of them last September.
The islands are also claimed by Taiwan.
Three Chinese ships spotted off disputed islands: Japan