The maritime incident near the disputed islets north of Taiwan has triggered anti-Japan sentiments in China [Reuters]

Police have ushered away dozens of Chinese protesters chanting anti-Japanese slogans outside the Japanese embassy in Beijing, amid tensions over a maritime incident last month.

The demonstrators gathered outside the building on Saturday, many shouting "Down with Japan" and "Down with Japanese imperialism", before hundreds of police moved them away from the site.

Officials had raised concerns that anger over the boat collision in disputed waters near an island group north of Taiwan claimed by both the countries could get out of control.

Recent weeks have seen a rise in anti-Japanese sentiment after a Chinese fishing boat captain after his vessel were seized after hitting two Japanese coast guard vessels.

Japan has returned the boat and its crew but continues to hold the captain, Zhan Qixiong, with China demanding his release.

"The boat captain is a hostage, and we came to tell Japan to hand him back and get out of the Diaoyu Islands," Hu Xu, one of the protesters, said using China's name for the disputed islands near where the Chinese boat was seized.

Disputed islands

The disputed islands, which are known as Diaoyu in China and as Senkaku in Japan, lie in an area with rich fishing grounds and that is believed to have sizeable oil and gas deposits. The islands are also claimed by Taiwan.

In China's financial hub, Shanghai, two men hung a banner saying "The Diaoyu islands belong to China ... return our captain" outside the Japanese consulate, while police warned them to be careful.
 

"We came here to appeal for fairness and for the right to ask for our captain back. We regret the government's weakness in diplomacy," Li Chunguang, one of the men said.

Saturday's protest coincided with the anniversary of the 1931 "Mukden Incident" that led to the Japanese occupation of China's northeast and eventually the brutal invasion and conquest of much of the country.

The date has in the past been marked by official commemorations and scattered anti-Japanese protests.

China's official Xinhua News Agency reported that protesters had also gathered to demand the boat captain's return in the northeastern city of Shenyang, previously known as Mukden, where the 1931 attack occurred.

Authorities have sought to forestall protests, blocking the websites of Chinese nationalist groups, telling university students not to protest and erasing discussion of organising demonstrations from the internet.

The website of the China Federation for Defending Diaoyutai remained offline on Saturday, and messages about organising protests over the incident were largely removed from online bulletin boards.

China has stated that the arrest of the fishing captain could damage relations and has summoned Japan's ambassador, Uichiro Niwa, repeatedly in the worst diplomatic spat between the two regional rivals in years.

Tokyo has warned its citizens in China to remain vigilant to ensure their safety in the event of any backlash over the dispute.