Taiwan's President Tsai Ing-wen has inspected a military drill on islands in the Taiwan Strait.

Tsai visited army, navy and air force bases on the Penghu Islands on Tuesday.

The president observed an exercise by a mechanized infantry unit. It was based on a scenario involving an enemy raid at a nearby airfield using five helicopters after reconnaissance by a drone.

In the drill, the Taiwanese unit simulated shooting down two enemy aircraft with mobile surface-to-air missiles, with troops from the remaining three copters descending to the ground.

The Taiwanese unit confirmed procedures for bringing the situation under control by using tanks and other equipment with enemy troops trying to occupy the base.

After the drill, Tsai delivered a speech. She said the units on Penghu hold a strategically important position and bear heavy responsibility. She also thanked the personnel for doing their utmost for the safety of Taiwan.

Concerns are growing in Taiwan that China may take military action following the recent presidential election victory by a candidate from the ruling Democratic Progressive Party.

Observers say Tsai's visit is aimed at showing people in and outside Taiwan that it is on full alert against the Chinese military during the Lunar New Year holidays starting next week.