Japan freed 14 crew members of a Chinese ship Monday nearly a week after their vessel collided with two Japanese patrol boats near disputed southern islets, but kept the captain in custody in a case that has angered China.

After authorities had questioned them, the 14 men left on a Chinese chartered plane that was sent to pick them up from where they were on a nearby Japanese island, said the Foreign Ministry, which arranged the flight back.

China has demanded that Japan release the entire crew, including the captain, Zhan Qixiong, who was arrested for allegedly obstructing official duties during the collision last Tuesday. A Japanese court has granted permission to prosecutors to keep him in custody until Sept. 19 to decide whether to formally indict him.

China has said the confrontation could damage its relations with Japan, underlining the sensitivity of the territorial dispute in the area. Beijing said Friday that it was postponing talks scheduled earlier with Japan on contested undersea deposits in the East China Sea, in a sign of its anger. The talks would have been the second meeting over the gas exploration related to the territorial dispute.

China’s State Councilor Dai Bingguo called in Japanese Ambassador Uichiro Niwa early Sunday -- the fourth time that he has been summoned over the incident. It is highly unusual for an official of Mr. Dai’s rank to intercede.

The incident occurred on Sept. 7, when the Chinese fishing boat collided with Japanese patrol vessels after ignoring warnings to leave the area near the disputed islands called Senkaku in Japanese and Diaoyu in Chinese, and refusing to stop for an inspection, Japan’s coast guard said.

The crew members were not arrested, but Japanese investigators were questioning them on a voluntary basis regarding the allegations of obstructing public duties as well as their suspected illegal fishing in the area, coast guard officials said.

A group of about 20 Chinese activists, meanwhile, planned to sail from the eastern coastal city of Xiamen to waters near the disputed islands.

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