A Chinese mainland spokeswoman has urged the Democratic Progressive Party administration in Taiwan to immediately release 14 mainland fishermen detained by the island.

Zhu Fenglian, a spokeswoman for the State Council's Taiwan Affairs Office, made the remarks on Wednesday after the island's coast guard forcibly boarded a mainland fishing boat and detained 14 crew members for allegedly "trespassing" on Jan 15.

"The island authority should respect the fact that fishermen from both sides of the Taiwan Straits have long been operating in the fishing areas," Zhu said. "They should stop their rude and dangerous treatment of the mainland fishermen and release them as soon as possible."

Zhu warned that the DPP will bear the consequences if it attempts to stir up trouble.

On Jan 15, coast guard officers were patrolling the waters of Huayu Island of Penghu, an archipelago of islands and islets in the Straits, when they came upon the fishing vessel, Taiwan media reported.

The officers used searchlights and broadcasts to warn the fishermen to halt. The fishermen refused, so the officers boarded the boat, the coast guard said in a news release on Jan 16.

A video posted online showed the officers threatening to shoot the fishermen, and the crew using brooms to defend themselves.

Fourteen crew members and about 4 metric tons of fish were found on the boat. After the coast guard detained the crew, the fish were thrown back into the sea, island media reported.

The fishermen were placed under quarantine and investigation in Taiwan after showing negative results in nucleic acid tests for the novel coronavirus that causes COVID-19.

Such incidents have happened frequently in recent years.

The Taiwan Affairs Office said that the mainland has always treated Taiwan fishermen like brothers.

Facilities for Taiwan fishermen have been set up in several coastal areas on the mainland to provide them with shelter, supplies and rescue assistance, it said.