Beijing: China said it had summoned Japan`s ambassador for a fifth time to demand Tokyo release a Chinese fishing boat captain arrested after a collision between his and two Japanese vessels in disputed waters.
China has accused Tokyo of provoking a "serious" problem in ties between the Asian neighbours.
Vice Foreign Minister Liu Zhenmin called in ambassador Uichiro Niwa on Tuesday to complain again over Japan`s continued "illegal detention" of the skipper, said a statement posted on the ministry`s website.
Liu "demanded that Japan immediately release and send back the Chinese boat captain."
After postponing planned talks with Tokyo on joint energy exploration in the East China Sea, where the Chinese trawler collided with two Japanese coastguard vessels, Beijing scrapped a trip to Japan by a senior lawmaker in protest.
Japan on Tuesday called the situation "extremely regrettable" but China went further, placing the blame squarely on Tokyo and demanding that the arrested skipper, facing up to three years in jail, be freed without delay.
"Japan provoked this serious situation and Japan should take all responsibility," foreign ministry spokeswoman Jiang Yu told reporters, adding it was "imperative" that the captain be released "immediately and safely".
"Taking into consideration all elements, China has decided to postpone the NPC delegation`s visit to Japan," she said, referring to the visit by a senior legislator and his delegation, which was to have started on Wednesday.
Japan said the skipper last week rammed two Japanese coastguard patrol vessels intentionally during a high-seas chase near the disputed islands, which are claimed by both countries as well as Taiwan.
Japan on Monday released the 14 crew of the trawler and allowed the boat to sail back to China, but the act has apparently done little to appease Beijing, incensed over what it reiterated was Japan`s "illegal" handling of the matter.
"The Chinese public has expressed its strong indignation over Japan`s illegal detention of the Chinese fishing boat," Jiang said.
"This fully embodies the Chinese people`s firm determination and resolve to defend China`s territory and sovereignty."
The uninhabited islands -- called Senkaku in Japan and Diaoyu in China -- lie in an area with rich fishing grounds that is believed to contain energy deposits, and which has been a frequent focus of regional tensions.
Japan`s ambassador to China, Uichiro Niwa, urged Beijing to rethink its decision to put off the East China Sea talks during a meeting with Chinese Assistant Foreign Minister Liu Zhenmin, Japanese news agency Kyodo reported, quoting an embassy press release.
Niwa accused China of "deliberately linking the fishing ship collision case with several unrelated issues" -- including the postponed talks -- Kyodo said.
Chinese officials have repeatedly summoned the ambassador to vent their fury over the incident, and also sent an inspection ship to the area, which confronted two Japanese survey ships at sea.
Referring to the cancellation of the senior Chinese lawmaker`s visit, Japan`s top government spokesman Yoshito Sengoku said: "If that is so, it is extremely regrettable."
Sengoku said he would have hoped for a frank exchange between both countries` lawmakers "because we are in this situation".
He reiterated Japan`s case that the Chinese skipper rammed the Japanese patrol vessels, adding: "We have to deal with the case in an orderly fashion under domestic law."
The Chinese captain, 41-year-old Zhan Qixiong, is being held on suspicion of obstructing officers on duty, a charge that carries a penalty of up to three years in prison. He has not yet been indicted, the step before a trial starts.
China`s state-controlled Global Times said Tuesday in an editorial that it would be the "last straw for Beijing" if Japan put the skipper on trial.