Beijing claims democratic Taiwan as part of its territory and has never renounced the use of force to bring the self-ruled island under its control.

Friday's visit to the Penghu islands in the strait separating Taiwan and mainland China comes as Beijing has ramped up military and political pressure on Taipei in recent years.

"I want to stress that the government will back all of you," Lai told sailors aboard the warship.

Penghu's location in the Taiwan Strait means it is likely to be on the front line of any potential invasion by China.

In July, Taiwan's military conducted a scaled-down live-fire drill during a typhoon in Penghu as part of its biggest annual "Han Kuang" wargames to simulate fighting enemy forces on its beaches.

Lai later had lunch with the troops at a navy camp stadium, in a tradition ahead of the upcoming Mid-Autum Festival.

"You are all an important force in safeguarding national security. I would like to thank you for your daily commitment," Lai told the crowd.

"Because all of you stick to your posts, the people can enjoy the holiday with peace of mind. The government will also have the troops' back".

Lai also pledged to improve the living conditions in the camps as well as weapons and equipments.

Lai has been labelled a "dangerous separatist" by China for his staunch defence of Taiwan's sovereignty, and Beijing conducted large-scale military drills around the island just days after his inauguration.

Taiwan's military has been reporting near-daily sightings of Chinese warships around its waters, as well as sorties by fighter jets and drones around the island.

The defence ministry said on Friday that 19 Chinese military aircraft and seven naval vessels and two official ships were detected in a 24-hour window ending at 6:00 am (2200 GMT Thursday).