TOKYO(Bloomberg) — Japan refused to release the captain of a Chinese fishing boat that collided with two Japanese Coast Guard vessels last week in disputed waters, ignoring China's repeated calls to free him.

Japan released the 14 remaining crew members, who flew back to China, and the boat also departed southern Ishigaki island for China, Chief Cabinet Secretary Yoshito Sengoku told reporters in Tokyo. The captain remains under arrest pending an investigation.

The collision took place in the East China Sea near islands known as Diaoyu in Chinese and Senkaku in Japanese claimed by both countries. Sovereignty over the area would give the holder rights to undersea gas and oil reserves. China broke off joint development talks on the energy resources following the captain's arrest.

"Japan's response to an illegal fishing operation by the Coast Guard and the investigation authorities are conducting are logical and appropriate," Sengoku said. "It's very troubling that the gas field exploration talks are being halted in connection with this. These are separate issues."

China State Councilor Dai Bingguo yesterday summoned Japanese Ambassador Uichiro Niwa for at least the third time and demanded release of the captain, crew and boat, state-run Xinhua News Agency reported yesterday. The foreign ministry released a statement later calling on Japan to make a "wise political resolution."

Niwa was summoned at 1 a.m. Japan time on September 12, an hour Sengoku called "regrettable." The ambassador "asked the Chinese side to respond calmly to this incident," Sengoku said.

Chinese Foreign Ministry spokeswoman Jiang Yu on September 9 called the detainment of the captain and crew "absurd, illegal and invalid," adding that "Japan will reap as it has sown if it continues to act recklessly."

Two Japanese Coast Guard vessels conducting oceanographic investigations were ordered to suspend operations by a Chinese warship, the Yomiuri newspaper reported. The ships were 280 kilometres (174 miles) west-northwest of the main island of Okinawa, in an area Japan claims as its exclusive economic zone, on September 11, according to the report. Japan filed a complaint with China over the incident, the Yomiuri said.