Taiwan will not bow to pressure from China and will continue its democratic way of life, as tensions over the island continue, President Tsai Ing-wen said on Sunday.

"The more we achieve, the greater the pressure we face from China," the BBC quoted Tsai as saying.

Her speech on Taiwan's National Day came after China's President Xi Jinping vowed to "fulfil reunification".

Taiwan considers itself a sovereign state, while China views it as a breakaway province.

Beijing has not ruled out the possible use of force to achieve unification, the BBC report said.

China has sent a record number of military jets into Taiwan's air defence zone in recent days. Some analysts said the flights could be seen as a warning to Taiwan's president.

Tsai said Taiwan was "standing on democracy's first line of defence". The island could not be forced to take "the path China has laid out for us", which she said did not offer freedom, democracy or sovereignty

China's military flights into Taiwan's air defence zone had seriously affected national security and aviation safety, she said, and the situation was "more complex and fluid than at any other point in the past 72 years".

Taiwan would not "act rashly" but would bolster its defences, she said.

She repeated an offer to talk with Chinese leaders on an equal footing, a suggestion Beijing, which brands her a "separatist", has so far rejected, the report said.

Tsai was re-elected by a landslide last year on a promise to stand up to Beijing.

Her speech was followed by a fly past of Taiwanese fighter jets.