Chinese State Councilor Dai Bingguo on Sunday told Japan to make a "wise political resolution" and immediately release the Chinese fishermen and fishing boat.

Rainbow is seen near the detained Chinese fishing trawler in Ishigaki Island of Okinawa Prefecture, Japan, Sept. 13, 2010. Fourteen Chinese fishermen detained by the Japanese authorities last week will be released on Monday. [Ji Chunpeng/Xinhua]

Dai, who made the remarks when summoning Japanese Ambassador to China Uichiro Niwa in the wee hours, was the highest-ranking Chinese official to make a response after the fishing boat and its crew were seized Tuesday.

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

Niwa said he would promptly report the Chinese position to his government, said the statement.

China decided Friday night to postpone a negotiation with Japan on the East China Sea issue scheduled for mid September, after the 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.

Protests of the public also emerged recently in China against the Japanese move.

On Wednesday, more than 40 Chinese nationals staged a protest near the Japanese embassy in Beijing over the detention of the Chinese fishing boat.

The Diaoyu Islands are 120 nautical miles northeast of Taiwan, 200 nautical miles west of China's mainland and 200 nautical miles east of Japan's southernmost island Okinawa.

The islands appeared on China's map since the Ming Dynasty ( 1368-1644). On a map published by Japan between 1783 and 1785, marking the boundary of the Ryukyu Kingdom, the Diaoyu Islands were shown as belonging to China.

Japan never questioned China's sovereignty over the islands before the Sino-Japanese war of 1894-1895.

Geographically the islands are attached to Taiwan. The waters around the islands are 100 to 150 meters deep and there is a 2,000- meter-deep oceanic trench between the islands and Japan's Okinawa islands.

Fishermen from China's Taiwan and Fujian and other provinces conducted activities such as fishing and collecting herbs in this area since the ancient times.