TAIPEI — China’s coast guard detained a Taiwanese fishing vessel and its five-member crew near the mainland’s southeast coast on Tuesday night, according to Taiwan authorities, in the latest flare-up of tensions in waters around a group of frontline islands controlled by Taipei.

In a statement, Taiwan’s coast guard said the fishing boat, Tachinman 88, was intercepted by two Chinese coast guard vessels near the Kinmen islands, which lie just miles from the Chinese city of Xiamen.

China coast guard officers boarded the fishing boat and then escorted it to a nearby Chinese port, the statement said, adding that three Taiwan coast guard vessels answered a call for help but retreated to avoid conflict when they were outnumbered by their Chinese counterparts.

In a news conference Wednesday, a senior Taiwan maritime official said the Taiwanese vessel was detained amid an annual summer fishing ban implemented by China in May.

Two Taiwanese and three Indonesian crew members were detained as the boat operated 11.2 nautical miles from the mainland coast in China’s territorial waters, said Hsieh Ching-chin, deputy director general of Taiwan’s Coast Guard Administration.

The Taiwan coast guard demanded the immediate release of the boat and crew members.

“The Coast Guard Administration calls on China not to engage in political manipulation, which undermines cross-strait relations, and it should release the Tachinman 88 vessel and its crew immediately,” the Taiwanese statement said.

Chinese authorities are yet to comment on the incident.

China’s ruling Communist Party claims self-governing Taiwan as its territory despite having never controlled it, and has vowed to unify with the island, by force if necessary.

And Beijing has ramped up pressure on Taipei since President Lai Ching-te, who it openly loathes as a “dangerous separatist,” won the island’s ruling Democratic Progressive Party a historic third consecutive term in power in January.

Meanwhile, tensions remain high in the waters around Kinmen, a group of outlying islands controlled by Taiwan but nestled just a stone’s throw from the shores of China.

China’s coast guard has increased patrols in waters around Kinmen and other outlying islands controlled by Taiwan since February, when two Chinese fishermen were drowned while being chased by Taiwan’s coast guard, who accused them of trespassing.

In late February, Chinese coast guard officers intercepted and boarded a Taiwanese tourist boat for inspection, an unprecedented move that startled Taiwanese passengers.

Taiwanese legislator Chen Yu-jen, who represents Kinmen for Taiwan’s opposition Kuomintang party, said since then, fishermen in the islands had been careful not to cross into China’s territorial waters due to Chinese coast guard patrols.

“Both sides of the Taiwan Strait do not currently have a warm relationship, so we should be more careful about staying inside our own waters,” she told CNN on Wednesday.

“Both sides of the Taiwan Strait should have better coordination. In the past, the coast guard would usually expel fishing vessels that crossed the maritime border, but now it is strictly enforcing the law.”

In a statement Wednesday, Taiwan’s Ministry of Agriculture said the incident took place in a “traditional fishing area” for fishermen from both sides of the strait.

“We hope that China can respect our operational rights,” it said. — CNN