China on Tuesday refused to release four Japanese held for "video graphing military targets" as Tokyo reasserted its sovereignty over disputed islands at the centre of a territorial spat between Asia's traditional rivals and biggest economies. The case of four Japanese men held last week for taking video pictures of "military targets" was "completely different from the incident in the (disputed) Diaoyu Islands,will be fairly handled in accordance with the law," Jiang Yu,the Chinese Foreign Ministry spokesperson told a media briefing here. China had informed Japan of the case and arranged for a consular visit in accordance with a China-Japan consular agreement,she said,giving no clue when they would be released. Except the allegation that they were caught video graphing military targets,China so far has not provided any information about them. The detention of the four men,employees of the Japanese urban redevelopment company Fujita Corp was stated to be one of the reasons why Japan released the skipper of a Chinese trawler who was taken into custody on September 7 off the Diaoyu Islands for damaging Japanese Coast Guard vessels. According to their company,they were in China as part of a project to dispose of chemical weapons abandoned by Japanese military in the country at the end of World War II. Diaoyu islands,also called Senkaku islands in Japanese,were administered by Tokyo while Japan,China and Taiwan claimed territorial rights over them. China has called off high-level exchanges with Japan and their relations,which were on mend in recent years,took a turn for worse after the incident. Japan's Foreign Minister Seiji Maehara asserted today that "no territorial issue exists" over an islands,saying its sovereignty was non-negotiable. According to Japanese news agency Kyodo,Maehara also defended the arrest of Chinese fishing boat captain as appropriate. The Chinese Foreign Ministry spokesperson blamed the "illegal detention of a Chinese trawler and its crew" for the worst dispute in years between Asia's traditional rivals and biggest economies. "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. Chinese Foreign Ministry spokesperson rejected Japanese demand to pay compensation to the coast guard vessels for damages caused by Chinese fishing trawler. "I would like say that Japanese coast guard intercepted Chinese fishing boat in Chinese territorial waters and collided with trawler and damaged it. So Japan should shoulder due responsibilities," Jiang said. "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," the official underlined. Jiang said the two sides must work together towards "practical actions" to prevent the deterioration in bilateral relations. "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," she said. "Whether China-Japan relations can be brought back on track depends on the attitude and actions of Japan," Jiang said. The official said she has no information about any chance meeting between Chinese Prime Minister Wen Jiabao and his Japanese counterpart Nato Kan at the Asian-European summit in Brussels on October 4-5.