Tensions may erupt again as a group of conservative Japanese politicians and political activists held a fishing campaign on Sunday in waters near the Diaoyu Islands to demonstrate "Japan's sovereignty", according to Japan's Asia News Agency.

A right-wing group called "Come on, Japan!" organized the campaign, according to the report. Six members of parliament and more than 40 activists from the group participated.

Yaeyama Fisheries Association of Okinawa Prefecture provided help and participants used 16 fishing boats of 5 to 10 tons each. "Setting off for a fishery study. I will arrive at 'the Senkaku Islands' early on Sunday morning. It is cloudy with waves rising," Tsutomu Takamura, 38, a member of the Democratic Party of Japan who participated wrote in his blog before departing for the campaign.

His companions included Youichiro Morioka, 37, of the DPJ, and Hakubun Shimomura, 58, a former deputy chief Cabinet secretary from the Liberal Democratic Party of Japan.

The provocations came after Japan's government criticized Uichiro Niwa, its ambassador to China, for warning that plans of the Tokyo municipal government to try to buy the Diaoyu Islands could spark a serious crisis.

Observers expressed worries that relations between Beijing and Tokyo would become more complicated, considering that the Diaoyu Islands are already one of the most strained flashpoints in the region.

Chen Yan, an expert at the Research Institute of Japanese Enterprises in Shanghai, told China Daily there is a growing dislike of China in Japan because it is "fashionable".

"The more dislike a Japanese politician shows for China, the more popular he or she will become."

Takamura, who graduated from Japan's Keio University and China's Peking University, once said in an interview with Reference News in Beijing that Sino-Japanese ties should be more than friendship.

Speaking of his younger alumnus in Keio University, Chen recalled Takamura was not "the head or in the vanguard of the opposition to China".

"Since it is 'in fashion', politicians sometimes need to play it up and win popularity. But their actions will have far-reaching consequences for Sino-Japanese relations."

The uncertain attitude of Tokyo has encouraged provocations from ambitious politicians.

The opposition party LDP has requested the Japanese government replace Niwa. Osamu Fujimura, the DPJ government's top spokesman, said at a news conference on Thursday that the foreign ministry had cautioned Niwa over his remarks, saying the ambassador's "personal opinions" did not represent the government's position.

Chinese navigational records show the islands as a part of China for many centuries, and even a Japanese map from 1783 shows them as a part of China.

"When both the internal political and economic situation is not stable, the Japanese government needs dislike for China to shift focus," Chen said.

wangchenyan@chinadaily.com.cn