Beijing sent a record number of military aircraft as well as warships and coast guard vessels to encircle Taiwan on Monday in the fourth major round of major drills in just over two years.

Taiwan deployed "appropriate forces" and put outlying islands on heightened alert in response to the exercises, which Beijing said were a "stern warning to the separatist acts of 'Taiwan Independence' forces".

On Friday, Lai visited air force, navy and coast guard facilities in northern Taiwan to thank personnel for "fully defending national security".

"Our determination to protect national sovereignty will not change," Lai said at a coast guard division near the capital.

"Our coast guard colleagues' determination to stabilise the society and ease the public mind... will not change. Our determination to protect fishing rights will not change."

Lai also praised the coast guard for dealing with China's grey-zone tactics with a "positive and decisive attitude" to "protect every inch of the territory".

Grey-zone manoeuvres refer to tactics that fall short of an act of war.

China claims self-ruled Taiwan as part of its territory and has said it will never renounce the use of force to bring the island under its control.

Beijing has ramped up military pressure on Taipei in recent years, sending warplanes and other military aircraft while its ships maintain a near-constant presence around the island's waters.

Lai, who took office in May, has been more outspoken than his predecessor Tsai Ing-wen in defending Taiwan's sovereignty, angering Beijing, which calls him a "separatist".