China is trying to turn democratic Taiwan into another Hong Kong, the island's foreign minister warned Tuesday as he met with a senior US official making a historic diplomatic trip.

That has caused alarm in Taiwan, a self-ruled island of 23 million people that Beijing claims as its own territory and has vowed to one day seize, by force if necessary.

Foreign minister Joseph Wu said Taiwan lives under the constant threat of having its freedoms taken away by China, during a rare meeting with US cabinet official Alex Azar in Taipei on Tuesday.

"Our lives have become increasingly difficult as China continues to pressure Taiwan into accepting its political conditions, conditions that will turn Taiwan into the next Hong Kong," he said.

President Tsai Ing-wen (right) with Alex Azar President Tsai Ing-wen (right) with Alex Azar Photo: Taiwan Presidential Office / Handout

"The people of Taiwan are all too familiar with dealing with threats, be it military, diplomatic or the threats of epidemics."

Health Secretary Azar is in Taipei for a three-day visit billed as the highest-level visit from the United States since it switched diplomatic recognition from the island to China in 1979.

Beijing has ramped up diplomatic, military and economic pressure on Taiwan since the 2016 election of President Tsai Ing-wen, who won a second term earlier this year with a landslide.

Photo: AFP / Kun TIAN

She rejects Beijing's stance that Taiwan is part of "one China" and instead views the island as "already independent".

Demonstrators attend a rally to show support for Hong Kong pro-democracy protests in front of the Chiang Kai-shek Memorial Hall in Taipei, in June 2020 Demonstrators attend a rally to show support for Hong Kong pro-democracy protests in front of the Chiang Kai-shek Memorial Hall in Taipei, in June 2020 Photo: AFP / Sam Yeh

China has suggested Taiwan could be granted a version of the "one country, two systems" model it uses for Hong Kong, which supposedly guarantees certain liberties and autonomy from the authoritarian mainland.

All mainstream political parties in Taiwan have rejected the proposal.

And what little enthusiasm there was for the idea has all but evaporated as China cracks down on Hong Kong's democracy movement.

Azar's trip comes as relations between the US and China are in tumult, with the two sides clashing over a wide range of trade, military and security issues, as well as the coronavirus pandemic.

On Monday, Taiwan said China sent fighter jets over a de facto border separating the two rivals in the Taiwan Strait shortly before Azar met President Tsai.

During his visit Azar has heaped praise on Taiwan's democracy and its success in battling the coronavirus.

He has previously criticised Beijing's handling of the pandemic, which emerged in central China, and its authoritarian model of government.

Taiwan, which has fewer than 500 confirmed COVID-19 cases including seven deaths, has been able to contain the virus because of its democracy and transparency, Wu said.

"In contrast to an authoritarian model where the authority is too crippled to disclose fact, in the transparent Taiwan Model, we simply can't afford to lie or conceal."

China has also managed to get its outbreak largely under control, with sweeping lockdowns and travel restrictions.

In contrast, the United States has the highest death toll with more than 160,000 fatalities.

US President Donald Trump has been accused by critics of taking a harder stance towards China to distract from his coronavirus response as he seeks re-election in November.