|Zhan Qixiong, a fishing trawler captain, flew out of Japan to the coastal Chinese city of Fuzhou on Saturday [AFP]
Japan has refused to apologise to Beijing for detaining a Chinese boat captain in disputed waters after Tokyo gave ground and released him.
China's foreign ministry said it was angry at the detention of the captain, arrested by Japan over two weeks ago after his trawler collided with two Japanese patrol boats in waters near islands that both sides claim.
The ministry demanded an apology and compensation and said China's claim to the islands, which it calls the Diaoyu and Japan calls the Senkaku, was "indisputable".
In response, Japan's foreign ministry said: "There is no territorial issue that needs to be resolved over the Senkaku.
"China calling for apology or compensation is groundless and is absolutely not acceptable."
Katsuya Okada, who was Japan's foreign minister until a cabinet reshuffle on September 17, criticised China over its demands, Japan's Kyodo news agency reported.
"Everybody knows that China is not a democratic country, but [the latest demand] will make that explicit," Okada, who is now secretary-general of the ruling Democratic Party of Japan, was quoted as saying.
Zhan Qixiong, a fishing trawler captain, flew out of Japan to the coastal Chinese city of Fuzhou on Saturday after being set free on Friday.
The release follows the detention of four Japanese nationals on suspicion of violating Chinese law regarding the protection of military facilities earlier this week.
Kyodo said Japanese diplomats met the four detainees on Saturday but Yoshito Sengoku, Japan's chief cabinet secretary, has denied a link between the two incidents.
The four have been under residential surveillance, meaning they were likely restricted at a hotel or lodging, the agency quoted an official at the Japanese embassy in Beijing as saying.
The statement from China's foreign ministry said that the two countries should solve their disputes through dialogue.
Naoto Kan, Japan's prime minister, also said it was time for Asia's two biggest economies to put relations back on a steady footing.
"I believe it is necessary for Japan and China to handle matters calmly," he said in New York, where he was attending the UN general assembly.
The dispute has underscored the brittleness of ties long troubled by Chinese memories of Japanese wartime occupation and territorial disputes over parts of the East China Sea that could hold rich reserves of gas.
Some Japanese newspapers decried Zhan's release as a backdown that would encourage Chinese assertiveness.
"There is a possibility that it has left an impression that Japan will cave in when pressured," Asahi Shimbun, a leading daily, said in an editorial.
Sun Cheng, an expert on relations between the two countries at the China University of Political Science and Law in Beijing, said it would take time for relations to improve.
"China will want to keep up its case over the Diaoyu islands. Whether Japan actually apologies or gives compensation is not so much the point as making it clear that China won't compromise on sovereignty," he said.