Japanese coast guards have been firing water cannon at dozens of Taiwanese boats near a chain of disputed islands.
The Taiwanese fleet, which includes fishing boats and armed coast guard vessels, entered the waters in the East China sea on Tuesday, according to the Japanese coastguard.
After Japan and China, Taiwan is the third country to lay claim on the islands, called Senkaku in Japan and Diaoyu in China.
Japanese coast guard vessels fired water cannon to turn away around 40 Taiwanese fishing boats and the accompanying Taiwanese coast guard vessels early on Tuesday morning, a government official said.
Osamu Fujimura, the Japanese cabinet secretary, said that the coast guard used water cannon and other measures to get the Taiwanese boats to change course.
"We've just lodged a protest with the Taiwan side," Fujimura told a news conference. "Our stance is that this is something that needs to be solved in the context of good bilateral ties between Japan and Taiwan. We would like to address the issue calmly."
Al Jazeera’s Steve Chao reporting from Japan’s Yonaguni islands said that Taiwan, which until now has not involved itself in the conflict, made its claim “very loudly” on Tuesday.
“[Japan’s] concern is not so much the fishing vessels, but the fact that they are being accompanied by about 10 Taiwan coast guard vessels,” Chao said.
The boats were part of a fleet that left Taiwan on Monday vowing to stake their claim to islands where they say they have ancestral fishing rights.
All the Taiwanese vessels had since left the territorial waters, the Japanese coast guard said.
According to Chao, Taiwan officials have said their coast guard ships were "armed and ordered to defend their vessels in the face of what they called, 'Japanese aggression.'"
Large-scale breach
Their arrival and large-scale breach of what Japan considers its territorial waters will further complicate an already high-stakes confrontation pitting Tokyo against Beijing.
China's Ministry of Agriculture, for its part, said that close to 200 Chinese boats have been fishing in seas around a group of rocky islands disputed with Japan.
The brief Chinese statement did not specify whether the boats were all there at one time, nor did it say how close they were to the islands. Beijing, which regards self-ruled Taiwan as a renegade province, may have included Taiwanese fishing vessels in its estimate.
Japan administers the uninhabited, but strategically well-positioned, archipelago under the name Senkaku. Beijing says it has owned the islands for centuries and calls them Diaoyu.
Taiwan, whose coast lies around 200 kilometres from the islands, claims the Diaoyutai belong to it.
Ownership of the islands, which have rich fishing grounds and potentially large oil and gas reserves, has become an important tenet of identity for all three claimants.
Relations between Japan and China have scraped hit a new low in recent weeks following Tokyo's nationalisation of three of the islands, which it bought from a private Japanese landowner.
Al Jazeera’s Marga Ortigas reporting from Hong Kong said that China has officially declared its ownership of the islands by submitting a map including them in its territory to the UN in September.
However, for the dispute to be resolved it would need to be taken to the International Court of Justice.
This is something that both countries don’t want, Ortigas said, “because neither country might be as certain that the courts will side with them in the dispute.”
“Talking is their only option, but there is still no idea about what the solution might be in the long run.”
Japan's coastguard said on Monday that two of China's maritime surveillance ships had spent seven hours in territorial waters around Uotsurijima, the largest island in the chain.
Two fisheries patrol boats briefly also entered the 12-nautical-mile zone around the chain, the coastguard said.
Rally against JapanTuesday morning's incident came after hundreds of slogan-chanting Taiwanese activists held a rally against Japan in Taipei on Sunday.
Chikao Kwai, the Japanese vice foreign minister, meanwhile, arrived in Beijing on Monday on a visit aimed at defusing the tensions.
"For Japan, Sino-Japanese relations are extremely important. The strategic development of Japan-China relations is also very important for Japan," said Kawai upon his arrival at the Beijing International Airport.
China on Monday announced that Kawai will discuss the islands dispute issue with his Chinese counterpart.
Yoshihiko Noda, the Japanese Prime Minister, called for calm as he himself departed to go to New York where he is scheduled to speak to the United Nations general assembly.
"I plan to talk about preventing conflict and looking towards a peaceful solution in my general speech. I also look to convey that as well as in bilateral meetings between the two countries," Noda said.