Under Lai's administration, Taiwan revamped training for its armed forces to include more nighttime drills and exercises as the democratic island faces greater pressures from China, which claims it as part of its territory.

On Tuesday night, Captain Hsieh Pei-hsun was forced to eject from his single-seat Mirage 2000 fighter jet after it apparently lost power during a training flight, the defence ministry said.

The jet crashed into the sea, while Hsieh was rescued about two hours later and transported to a hospital in central Taichung city.

Lai visited Hsieh at the hospital Wednesday, and said his condition is stable.

"The people should also know that in order to protect the country, the armed forces not only stick to their posts but also train day and night," Lai told reporters after his visit.

"I ask the people to fully support the military and be the backing of the military. This way the military will have more strength to protect the country. Only by defending the country can we have a stable society," he said.

The air force said it will set up a special task force to investigate and clarify the cause of the incident.

China in recent years has increasingly used fighter jets, drones and naval vessels around Taiwan, which military experts call a grey-zone tactic that serves to exhaust the island's armed forces.

In a 24-hour window ending 6 am Wednesday (2200 GMT Tuesday), 21 Chinese military aircraft, nine naval vessels and an official ship were detected around the island, Taiwan's defence ministry said.

A subsequent statement said that a further 19 Chinese fighter jets, patrol aircraft and drones were tracked around Taiwan, and the defence ministry was monitoring the situation.

Beijing has said it would never renounce the use of force to bring Taiwan under its control.

Three days after Lai was inaugurated as president in May, China launched war games to simulate a blockade around the island.