China claims democratic Taiwan as part of its territory and has never renounced the use of force to bring it under Beijing's control.

Friday's 66th anniversary of the Chinese assault on the Kinmen islands -- known as the "823 bombardment" after the date on which it began -- comes as China has ramped up military and political pressure on Taiwan in recent years.

Controlled by Taiwan, the islands lie just five kilometres (three miles) from the Chinese coast.

Lai, who took office in May, laid a wreath to commemorate the bombardment's victims at a cemetery during his first trip to Kinmen as president.

China's People's Liberation Army fired 470,000 shells at Kinmen and nearby islets in 1958, killing 618 servicemen and civilians in an attack that lasted 44 days.

"We must be determined to protect Taiwan" and carry on the spirit of the soldiers who faced the 823 bombardment, he said at a banquet attended by veterans and their families.

"At present, the threat Taiwan, Penghu, Kinmen and Matsu face from China is no less than previous years," he said, referring to other outlying island chains under Taipei's control.

"If we want to resist the threat from China in the future, we must unite as one... We have only one goal -- defend national sovereignty and safeguard democracy".

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.

On Friday, the defence ministry said 41 Chinese military aircraft and seven naval vessels were detected in a 24-hour window ending at 6:00 am (2200 GMT Thursday).

A second statement said a further 27 aircraft had been spotted since as Beijing conducted a "joint combat patrol" drill.

"The armed forces have monitored the situation and employed aircraft, Navy vessels and coastal missile systems in response to the detected activities," it said in the statement.