Taiwan will keep bolstering its defences to ensure nobody can force them to accept the path China has laid down that offers neither freedom nor democracy, President Tsai Ing-wen said on Sunday, in a riposte to Beijing that its government denounced.

Claimed by China as its own territory, Taiwan has come under growing military and political pressure to accept Beijing's rule, including repeated Chinese air force missions in Taiwan's air defence identification zone, to international concern.

Chinese President Xi Jinping vowed on Saturday to realise "peaceful reunification" with Taiwan and did not directly mention the use of force. Still, he got an angry reaction from Taipei, which said only Taiwan's people can decide its future.

Addressing a National Day rally, Tsai said she hoped for an easing of tensions across the Taiwan Strait, and reiterated Taiwan will not "act rashly".

"But there should be absolutely no illusions that the Taiwanese people will bow to pressure," she said in the speech outside the presidential office in central Taipei.

"We will continue to bolster our national defence and demonstrate our determination to defend ourselves in order to ensure that nobody can force Taiwan to take the path China has laid out for us," Tsai added.

"This is because the path that China has laid out offers neither a free and democratic way of life for Taiwan, nor sovereignty for our 23 million people."