Taiwan's coast guard held drills with the military on Sunday to better practice joint operations in the face of what the government in Taipei says is a growing "grey zone" threat from China, which claims the island as its own territory.

Democratically governed Taiwan has repeatedly complained about activities such as undersea cable cutting and sand dredging by China around the island, designed to pressure it without direct confrontation.

It is often Taiwan's coast guard that scrambles first to respond.

The drills in the southern port city of Kaohsiung, overseen by President Lai Ching-te, simulated the seizing of a ferry by "international terrorists." The coast guard worked with an interior ministry rescue helicopter and army medevac helicopter to board and take back control of the boat and evacuate casualties.

A navy anti-submarine helicopter flew over the scene as the drill ended, along with the medevac and rescue helicopters, the first time they have flown together in such a scenario, the coast guard said.

"Taiwan has been facing constant grey intrusion from China, but our coast guard colleagues have always been on the front line to enforce the law and protect the lives and safety of the people of Taiwan," Lai told the audience for the drills, which included the top U.S. diplomat in Kaohsiung, Neil Gibson.

"The government will continue to consolidate the strength of all departments and strengthen the resilience of the entire society to defend national security and safeguard Taiwan's democracy and freedom," Lai said.

Taiwan's coast guard, which would be pressed into military service in the event of war with China, is also routinely sent out to shadow Chinese ships during Beijing's war games around the island.

The coast guard, like the navy, is in the midst of an expansion and modernisation program.

Its new Anping-class corvettes, which began being commissioned in 2020, are based on the navy's Tuo Chiang-class warships. They are state-of-the-art, highly maneuverable stealth vessels meant to take out larger warships while operating close to Taiwan's shores.

The Anping-class ships, one of which took part in the drill, have space for launchers for the Taiwan-made Hsiung Feng anti-ship and sea-to-land missiles, as well as added equipment for rescue operations.

Taiwan's government rejects Beijing's sovereignty claims, saying only the island's people can decide their future.