Chinese State Councilor Dai Bingguo told Japan early Sunday morning to make a "wise political resolution" and immediately release the Chinese fishermen and fishing boat its coast guard seized earlier this week.

The Chinese trawler under detention stops at the harbor of Ishigaki, Okinawa, Japan, Sept. 9, 2010. Japan Coast Guard sent the captain of the Chinese trawler which collided with Japanese patrol ships in waters off Diaoyu Islands to prosecutors in Okinawa Prefecture Thursday morning. [Xinhua/Ji Chunpeng]

Dai made the remarks when he summoned the Japanese Ambassador to China Uichiro Niwa in the wee hours. He was the highest-ranking Chinese official to make a response after the fishing boat and its crew were seized Tuesday in waters off the Diaoyu Islands and its captain was detained on Friday.

"Dai expressed solemnly (to the Japanese ambassador) the Chinese government's grave concerns and its serious and just position," said the Foreign Ministry in a statement.

Dai warned Japan not to make a wrong judgement on the situation and urged it to make a "wise political resolution" and immediately release the fishermen and return the boat.

The Japanese ambassador expressed that he would promptly report the Chinese position to his government, according to the statement.

China decided Friday night to postpone a negotiation with Japan on the East China Sea issue, which had been scheduled for mid September, after a Japanese court ruled a 10-day detention through Sept.19 against the captain despite protests from China.

Previously, Foreign Minister Yang Jiechi on Friday summoned the Japanese ambassador and demanded Japan immediately and unconditionally release the boat and all the crew, saying China's determination to defend its sovereignty over the Diaoyu Islands and the interests of the Chinese people was unswerving.

Foreign Ministry spokeswoman Jiang Yu said Friday night when announcing the postponement of the talks that the Japanese side has "ignored China's repeated solemn representations and firm opposition, and obstinately decided to put the Chinese captain under the so-called judiciary procedures."

She said Japan's acts have violated the law of nations and basic international common sense, and are "ridiculous, illegal and invalid."

"Japan will reap as it has sown, if it continues to act recklessly," Jiang warned.

On Tuesday, two Japanese Coast Guard patrol ships and the Chinese fishing boat collided in waters off the Diaoyu Islands in the East China Sea. No injuries were reported, but the fishing boat was then intercepted by the Japanese patrol.