Japan frees Chinese trawler crew, holds captain

The incident has sparked diplomatic arguments between the Asian powers, with China calling off planned talks over oil and gas fields in a contested area of the East China Sea and summoning Tokyo's ambassador four times to protest.

Japan government spokesman Yoshito Sengoku said questioning of the crew had been completed, meaning there was no reason to keep them in Japan, and that prosecutors had also finished collecting evidence from the ship.

The 14 people who had been investigated are being returned to China, and the ship will be returned by an acting captain.

The fishing boat's captain, Zhan Qixiong, was arrested last week on suspicion of obstructing officers on duty. This charge carries up to three years' prison, and a court has since approved his continued detention.

"We will handle this as a criminal case based on Japanese domestic law," Sengoku told a press briefing.

Tokyo suspects the trawler captain deliberately rammed the two Japanese vessels near the disputed island chain between Japan's Okinawa island and Taiwan, known as Senkaku in Japan and Diaoyu in China.

Four Japanese patrol boats later pursued and seized the Chinese trawler.

The uninhabited islands are claimed by Tokyo, Beijing and Taipei and are a frequent focus of regional tensions.

There are four controversial Chinese gas fields in the sea that Japan says extend into its own exclusive economic zone.

The row has cast a cloud over what had been a steady improvement in relations between the traditional East Asian rivals in recent years, as their economic relationship has deepened.

The dispute escalated on Saturday when a Chinese vessel confronted two Japanese survey ships at sea, and Beijing called off talks with Tokyo set for later this month over their competing maritime claims in the area.

The Chinese foreign ministry said any evidence collected by Japan on the collision would be "illegal, invalid and in vain".