Chinese officials have boarded and seized a Taiwanese fishing boat operating near China's coast close to a Taiwan-controlled island and took it to a Chinese port, Taiwan's coast guard says, in a further escalation of tensions.
China views democratically governed Taiwan as its own territory and has ramped up pressure on Taipei since May when President Lai Ching-te took office, a man Beijing accuses of being a "separatist".
The squid fishing boat was near the Taiwan-administered Kinmen islands, which sit next to the Chinese cities of Xiamen and Quanzhou, but in Chinese waters on Tuesday night when it was boarded and seized by two Chinese maritime administration boats, Taiwan's coast guard said.
The Taiwanese boat was operating during China's no-fishing period, the coast guard said, adding Taiwan would communicate with China and urge them to release the fishermen as soon as possible.
Coast guard officials in southern Fujian seized the Taiwan boat, China's coast guard said, because it violated a summer ban on fishing and carried out illegal trawling operations.
The nets used were also far smaller than the minimum size so damaged marine fishery resources and the environment, it said in a statement.
Taiwan vessels tried to "interfere with" China's normal law enforcement, and the Fujian officials warned and "drove them away" in line with the law, it said.
China should explain why it seized the boat, Taiwan deputy director-general Hsieh Ching-Chin says. (AP PHOTO)
China's Taiwan Affairs Office did not immediately respond to a request for comment.
Taiwan sent its own coast guard ships to assist and broadcast warnings asking China to release the fishing boat but China's ships broadcast back saying not to interfere, Taiwan's coast guard said.
Taiwan's ships then backed off to avoid a conflict and the Taiwanese fishing vessel was then taken to a Chinese port, it said, saying three of the five fishermen were Indonesian migrant workers.
Taiwan Coast Guard Administration deputy director-general Hsieh Ching-chin told reporters that China should explain why it had seized the boat, and pointed out that in previous cases, fishermen had been released after paying fines when operating during China's no-fishing season.
Taiwanese fishing boats needed to raise their alert level and the coast guard would also strengthen its patrols, he said.
"The coast guard also calls on the mainland side not to use political factors to handle this situation," Hsieh said.
Taiwan's top China policy-making body, the Mainland Affairs Council said, it would seek an explanation from China about what had happened and "dispel unnecessary speculation".
This is not the first time a Taiwan fishing boat had been taken by Chinese authorities after operating in that country's waters, an official said, speaking on condition of anonymity.
A Taiwan official familiar with the island's security planning told Reuters they had issued alerts to fishing and transport authorities around Taiwan about "possible risks" amid Chinese coast guard activities in the region, including near Japan and the Philippines.
Chinese maritime enforcement and coast guard ships have been regularly operating around Kinmen since February after two Chinese fishermen died trying to flee Taiwan's coast guard.