China has not ruled out using force to bring the democratic island under its control, which Lai and his government oppose.

"I will also uphold the commitment to resist annexation or encroachment upon our sovereignty," Lai said under grey skies during Taiwan's National Day celebrations.

Beijing and Taipei were "not subordinate to each other" and China had "no right to represent Taiwan", Lai said.

Beijing has ramped up pressure on Taiwan to accept its territorial claims and relations have remained tense under Lai, who took office in May.

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

China warned Thursday evening after the speech that Lai's "provocations" would result in "disaster" for the people of Taiwan.

"(Lai's) provocations in seeking 'independence' are the root cause of trouble for peace and stability in the Taiwan Strait and will bring disaster to the people of Taiwan," said Chen Binhua, a spokesman for China's Taiwan Affairs Office, according to a social media post by the bureau.

Earlier in the day, China's foreign ministry spokeswoman Mao Ning condemned Lai's speech, saying it "exposed... his sinister intention to escalate tensions in the Taiwan Strait for political self-interest".

A senior US administration official said Wednesday that Beijing may use the National Day celebrations "as a pretext" for military exercises.

Speaking in front of an audience that included Tsai and pro-independence former Taiwan president Chen Shui-bian, Lai said: "Our determination to defend our national sovereignty remains unchanged."

"Our efforts to maintain the status quo of peace and stability in the Taiwan Strait remain unchanged," Lai said in front of the Presidential Office.

- US politicians guests -

Foreign guests included three members of the US Congress, as well as representatives from some of the 12 states that still have diplomatic relations with Taiwan, including Tuvalu Prime Minister Feleti Teo.

The United States switched diplomatic recognition from Taipei to Beijing in 1979 but has remained Taiwan's most important partner and its biggest arms supplier.

Washington opposes Taiwan independence and any attempt by China to forcibly take the island.

Thursday's celebrations mark the 113th anniversary of the toppling of China's Qing dynasty and the subsequent founding of the Republic of China.

The current dispute between China and Taiwan dates back to a civil war between the nationalist forces of Chiang Kai-shek and Mao Zedong's communist fighters.

The nationalists fled to Taiwan in 1949 after they were defeated by the communists.

The Republic of China remains Taiwan's official name.

While Taiwan has its own government, military and currency, it has never declared formal independence from mainland China.

Beijing has sought to erase Taipei from the international stage, blocking it from global forums and poaching its diplomatic allies.

- 'Fears in mind' -

Taiwan was on alert for Chinese military drills near the island on National Day after observing "some maritime deployments", a senior security official told AFP on Wednesday.

China maintains a near-daily military presence around Taiwan and has held three rounds of large-scale war games in the past two years, deploying aircraft and ships to encircle the island.

"Even though we have not seen significant military activity or exercises following previous 10/10 speeches, we are prepared that Beijing may choose to use this as a pretext this year," the senior US administration official told reporters.

"We see no justification for a routine annual celebration to be used in this manner. Coercive actions like this against Taiwan and in the cross-Strait context, in our view, undermine cross-Strait stability."

Taiwan's defence ministry said Thursday that 27 Chinese military aircraft and nine navy vessels were detected around the island in the 24 hours to 6:00 am.

Susan Hung, 60, told AFP she worried that China's military actions around Taiwan could "escalate beyond control".

"We have these fears in mind, so we hope for peace," Hung said, as she watched the celebrations.

In his speech, Lai expressed hope for "healthy and orderly dialogue and exchanges" with China, and urged Beijing to use its influence to help end conflicts in the Middle East and Ukraine.

Beijing severed high-level communications with Taipei in 2016 when Tsai, also a member of Lai's Democratic Progressive Party, took power.

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