Protesters from Taiwan planned to sail to the Diaoyu Islands on Tuesday to proclaim China's sovereignty but failed after eight naval ships sent by the Japanese coast guard obstructed the plan.

China kept up its pressure on Japan Wednesday by calling its ambassador again to demand the immediate release of a Chinese fishing boat captain who Beijing says has been illegally held since last week.

Analysts warned that any delay in resolving the issue on Japan's part would complicate the issue, as a sense of dissatisfaction among the Chinese public became increasingly noticeable and a diplomatic crisis seemed to be brewing.

Assistant Foreign Minister of China Liu Zhenmin again complained to the Japanese ambassador, Uichiro Niwa, over the issue late Tuesday and demanded that the boat's captain, Zhan Qixiong, be sent back to China, the Chinese foreign ministry said on its website.

It was the fifth time that the Japanese envoy has been summoned over the demand.

The Chinese fishing boat that was detained by the Japanese Coast Guard arrived at the Shenhu fishing port in Jinjiang of Quanzhou city in East Fujian Province at 8:30 am Wednesday, two days after a chartered flight took 14 Chinese fishermen back to Fuzhou, capital city of Fujian.

The Chinese trawler was illegally detained by Japan after it collided with two Japanese Coast Guard patrol vessels September 7 off the Diaoyu Islands in the East China Sea.

Huang Dahui, a professor of Japanese politics at Renmin University of China, said the relationship between the two peoples is key to bilateral ties, which are at risk of being damaged.

"Since the 1970s, Japan has attached great importance to public diplomacy in an effort to rebuild and promote its image. While for China, a country that had been subject to its military aggression, a ruined public impression toward it is definitely against Tokyo's efforts in that regard. It would have an impact on political relations," Huang said.

The caution came as public sentiment in China continued running high over the dispute.

Li Nan, a member of the China Federation of Defending the Diaoyu Islands in Beijing, told the Global Times that the organization is considering demonstrations this weekend.

"We'll also manage to sail to the seas near the Diaoyu Islands to protest the illegal holding of the Chinese captain," Li said.

A blogger commented on cfdd.org.cn, the website of the group, saying, "The protesters have my full support. It's worth dying to safeguard national sovereignty."

Protesters from Taiwan planned to sail to the Diaoyu Islands on Tuesday to proclaim China's sovereignty but failed after eight naval ships sent by the Japanese coast guard obstructed the plan, according to local reports. After a five-hour standoff, the protesters had to return to Taiwan.

Fan Liqing, a spokesperson of Taiwan affairs for the State Council, said Wednesday that protecting the Diaoyu Islands' sovereignty is in the interests of both the Chinese mainland and Taiwan.

Tensions over the issue are high enough that a press officer at the Japanese embassy in Beijing told the Global Times that the embassy would advise Japanese in China to avoid direct confrontations with locals.

Foreign ministry spokesperson Jiang Yu said Tuesday that Chinese people are determined to protect the country's sovereignty, but the government won't support extremism, and it believes that the public will express its feelings rationally.