NAHA, Okinawa — Japanese Maritime Safety officials are looking into why a Chinese ship was conducting an unauthorized survey of the waters near Hateruma, an island in the southernmost part of the prefecture.

A Japanese coast guard airplane spotted a Chinese ship conducting what appeared to be unauthorized marine research in Japanese water at about 5:55 p.m. Nov. 7 about 10 miles west of the island, according to an 11th Maritime Safety Headquarters spokesman.

The ship, Fendou 7, was moving south at a speed of about 11.5 mph, said Seiji Yanagida, 11th Maritime Safety Headquarters security chief. A patrol boat was dispatched to monitor the activity.

At 12:48 a.m. Nov. 8, a patrol boat crew member reported cables were thrown into the ocean from the ship’s stern. At the time, Fendou 7 was about 58 miles south of Hateruma, within Japan’s exclusive economic zone, Yanagida said.

When questioned by the Japanese coast guard, the ship’s crew said they were conducting a seismic survey, Yanagida said.

“The Maritime Safety Agency continued issuing warning to discontinue the activity, as no such activity was authorized,” he said.

The Fendou 7 paid no heed to the warnings and continued its activity throughout the day, he said.

“The agency reported the above mentioned situation to the Ministry of Foreign Affairs, which filed a protest and request to cease the activity through the diplomatic route,” Yanagida said.

At 11 a.m. Sunday, Fendou 7 notified the Japanese patrol boat it had been directed by the Chinese government to suspend the survey, retrieve its equipment and return to Shanghai, Yanagida said. The ship moved out of the area about 1:40 a.m. Monday.

“At about 11:50 p.m. Monday, the survey ship moved out of Japan’s exclusive economic zone at a point about 135 kilometers (81 miles) southwest of Hateruma,” he said. “At 1:16 a.m. Tuesday, it disappeared from the radar of the patrol ship. At that point, the patrol boat discontinued monitoring.”

Yanagida said it was the 10th time this year a Chinese ship had entered Japanese waters to conduct a survey.

“Of the 10 surveys, three cases, including this one, had no prior request,” he said. “Proper requests were made in the other seven cases. We strictly respond when any ship violates the international rule.”

Meanwhile, a Maritime Self-Defense Force plane crew sighted a surfaced Chinese submarine Wednesday off Kagoshima Prefecture, north of Okinawa Prefecture.

Maritime agency officials said it was the first time a Chinese Ming-class submarine has been spotted on the surface in waters around Japan.

The submarine was sighted at approximately 8 a.m. heading west about 36 miles east of Cape Sata, in international waters between Kyushu and the Osumi Islands, according to agency officials.

Japanese officials said they did not know why a Chinese submarine would be in the area, The Associated Press reported. It is not clear if Tokyo will seek an explanation from China.

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