China’s Coast Guard seized a Taiwanese fishing boat and its crew of five and forced it to a port on the mainland Chinese coast, in the latest move by Beijing that is likely to increase pressure on President Lai Ching-te of Taiwan.

The fishing boat, Ta Chin Man 88, was in Chinese waters 27 miles northeast of Kinmen, a Taiwanese-controlled island close to the Chinese coast, when two Chinese Coast Guard ships boarded and took control of it on Tuesday night, Taiwan’s Coast Guard Administration said. Taiwanese Coast Guard vessels that sailed toward the area to help the fishing boat were blocked by their Chinese counterparts, the administration said.

The seas around Taiwan, a self-governed island that China claims as its own, have become more and more tense, with coast guard standoffs between the two sides seemingly on the rise. The concern among officials and analysts is that if such encounters become frequent, it could raise the risk of a clash that could set off a broader crisis among world powers.

The Taiwanese Coast Guard vessels broadcast demands to the Chinese Coast Guard to free the fishing boat, but the Chinese responded only by “demanding no interference,” the statement from Taiwan said. The fishing boat had two crew members from Taiwan and three from Indonesia, officials said. Many workers on Taiwanese fishing boats come from Indonesia and other Southeast Asian countries.

Hsieh Ching-chin, a spokesman for Taiwan’s Coast Guard Administration, said the Ta Chin Man 88 had entered Chinese territorial waters. The boat may have been seized because China has been more actively enforcing an annual moratorium on fishing in those waters since May 1, he said.

“This year, China is different from the past, with stronger law enforcement during the fishing moratorium,” Mr. Hsieh said at a news conference on Wednesday. Mr. Hsieh told reporters that China has seized 17 Taiwanese fishing boats since 2003 and that the last such incident was in 2007.