Lai made the remarks during a visit to the Kinmen islands off China for the 75th anniversary of a victory over communist forces in the Battle of Guningtou.

It followed a fortnight of intense military activity in the Taiwan Strait -- the sensitive waterway that separates China and Taiwan -- with troops from both sides holding drills.

"(We) will not yield an inch of ground in Taiwan, Penghu, Kinmen and Matsu to firmly defend our homeland," Lai said in a speech, referring to the islands controlled by Taipei.

"The Battle of Guningtou lets us understand that democracy and freedom should not be taken for granted, but require the joint efforts of generations to defend them," Lai said.

Without naming China, Lai insisted that "any external forces" would not be allowed to change the future of the islands.

China's Communist Party has never ruled democratic Taiwan, but Beijing claims the island as part of its territory and has said it will never renounce the use of force to bring it under its control.

The dispute between Beijing and Taipei dates back to a civil war between Mao Zedong's communist fighters and Chiang Kai-shek's nationalist forces, which fled to Taiwan in 1949 following their defeat.

The nationalists scored a key victory over the communists in the Battle of Guningtou on the Kinmen islands.

Lai, who took power in May and has been more outspoken than his predecessor in defending Taiwan's sovereignty, earlier attended a sombre ceremony for the battle and shook hands with veterans.

In his speech, Lai said Taiwan's "determination to defend our national sovereignty" and efforts "to maintain peace and stability across the Taiwan Strait" were unchanged.

And he repeated his hope that China and Taiwan will "conduct dialogue and exchanges with parity, dignity and in a healthy and orderly manner".

Beijing severed high-level communications with Taipei in 2016 and has since ramped up military and political pressure on the self-ruled island.

China's large-scale war games around Taiwan on October 14 were followed by live-fire drills near the island on Tuesday, and the transiting of a Chinese aircraft carrier group through the Taiwan Strait a day later.

Taiwanese troops conducted live-fire drills on Penghu island in the waterway on Thursday, days after a US and a Canadian warship sailed through the narrow passage.