China on Tuesday demanded Japan take practical measures to bring ties back on track after they were strained by the collision of a Chinese trawler and two Japanese patrol boats earlier this month.

"If Japan takes its ties with China seriously, Japan should take practical measures to remove the negative effects of the incident and mend bilateral relations," Chinese Foreign Ministry spokeswoman Jiang Yu told a regular press briefing Tuesday.

The collision occurred in waters off the Diaoyu Islands, which are claimed as Chinese territory, on Sept. 7. Japan then seized the Chinese trawler and detained the trawler's captain and 14 fishermen on board.

China repeatedly protested, claiming the detentions were illegal, and made representations following the incident.

"Japan's illegal detention of a Chinese trawler and its crew sparked the strong indignation of the Chinese people and severely undermined the bilateral relationship," Jiang said.

China's countermeasures were triggered by Japan's moves, she said.

China decided to halt bilateral exchanges at and above provincial and ministerial levels. It also suspended contact with Japan on the issue of expanding aviation rights between the two countries.

Jiang said Japan should assume responsibility for the incident as the Japanese patrol ships had obstructed and intercepted the trawler in Chinese seas, damaged the Chinese fishing boat in the process.

"China highly values its ties with Japan, but safeguarding bilateral relations requires the two sides to work together towards the same goal and requires Japan to take practical actions," Jiang said.

"Whether China-Japan relations can be brought back on track depends on the attitude and actions of Japan," Jiang said.

Asked about Chinese fisheries law enforcement boats patrolling off the Diaoyu Islands, Jiang said the waters off the Diaoyu Islands were traditional Chinese fishing grounds.

Chinese fisheries law enforcement boats were patrolling in accordance with the Chinese law and aimed to keep order and ensure the safety and property of Chinese fishermen, Jiang said.

"We call for Japan to stop its stalking and disruption of Chinese fisheries law enforcement boats," Jiang said.

Asked about China's investigations into four Japanese nationals who allegedly entered a military zone in north China's Hebei Province without authorization and illegally videotaped military targets last week, Jiang said the case was being heard.

China had informed Japan of the case and arranged for a consular visit in accordance with a China-Japan consular agreement, Jiang said.

"The case, which is completely different from the incident in the Diaoyu Islands, will be fairly handled in accordance with the law," Jiang said.