A Chinese coast guard ship equipped with what appeared to be four gun turrets was sighted near disputed islands in the East China Sea, the Japan Coast Guard said Wednesday.

Chinese coast guard vessels regularly sail near the islets, but a Japanese Coast Guard spokeswoman said it is the first time an armed Chinese coast guard ship has been spotted in the area. For its part, China said the vessel was carrying standard equipment and was doing nothing wrong in Chinese waters.

"We have delivered our strong protest and requested (the Chinese coast guard) to stop the activities near the Senkaku Islands immediately," Takako Ito, a spokeswoman for Foreign Ministry in Tokyo, said in an email.