Dozens of Taiwanese boats, including six coastguard vessels, entered territorial waters around disputed East China Sea islands on Tuesday, the Japanese coast guard has said.
Japanese vessels fired water cannon to turn away around 40 Taiwanese fishing boats and eight 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. All the Taiwanese vessels had since left the territorial waters, the Japanese coast guard said.
Japanese public broadcaster NHK showed footage of a Japanese coast guard ship shooting water at a Taiwan fishing boat, while a Taiwan patrol vessel blasted water at the coast guard ship in reply.
"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."
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.
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.
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.
Tuesday morning's incident came after hundreds of slogan-chanting Taiwanese activists held a rally against Japan in Taipei on Sunday.
Talks due to commence
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.