An outraged Chinese public has been flooding the Internet with its intense displeasure and protests over Japan's illegal detention of a Chinese trawler and its crew in the past few days.

Japan detained Chinese captain Zhan Qixiong and his fellow crew of 14 members on September 7 after the trawler they were abroad collided with two Japanese coast guard patrol vessels near the Diaoyu Islands in the East China Sea.

The crewmembers and the boat returned to China on September 13, but Japan extended the illegal detention of Zhan by 10 days on Sunday.

Since the incident, "Diaoyu Islands" and "Zhan Qixiong" have become the most searched terms in China's Internet community, the world's largest online community with more than four billion Internet users.

Also, Internet bulletin boards on several major Chinese news portals have been overwhelmed with tens of thousands of messages saying that the Diaoyu Islands have always been an integral part of China and it's within the rights of Chinese fishermen to fish in the waters around the islands.

Above all, these messages call for Japan to immediately and unconditionally release Zhan.

"The seizure of our trawler and captain causes an enormous damage to the Chinese people. I strongly demand that Japan return the seized trawler and apologize," said a netizen on Sohu.com, who goes by the name of "1996."

On Sunday, China's Foreign Ministry said that China's relations with Japan were being severely damaged by Japan's decision to prolong Zhan's detention, warning that China would take "strong counter measures" if Japan did not release him.