A Chinese government vessel on Saturday asked a coast guard survey ship operating in Japan's exclusive economic zone to stop its activities, coast guard officials said.
The survey ship was located about 280 km north-northwest off Okinawa Island when the request was made at 7:40 a.m. The ship notified the Chinese vessel of the purpose of its activities and continued surveying operations for nearly two more hours, according to the coast guard.
Japan later lodged a protest to China over the incident through diplomatic channels, it said.
The incident occurred at a time when diplomatic tensions between the two countries are rising after collisions between a Chinese trawler and two Japan Coast Guard patrol boats near the disputed Senkaku Islands in the East China Sea, which led Japan to arrest the Chinese ship's captain.
On Friday, an Okinawa Prefecture court granted a prosecutors' request for a 10-day detention for the skipper.