US House of Representatives Speaker Nancy Pelosi has addressed Taiwan’s parliament and met its president, ahead of a meeting with human rights activists, during a visit to the island that has infuriated Beijing.

China condemned the highest-level US visit to Taiwan in 25 years as a threat to peace and stability in the Taiwan Strait, responding with a flurry of military exercises, summoning the US ambassador in Beijing, and announcing the suspension of several agricultural imports from Taiwan.

The Chinese Foreign Ministry released a lengthy statement, saying it would “definitely take all necessary measures to resolutely safeguard its sovereignty and territorial integrity”. It said Ms Pelosi’s visit had “a severe impact on the political foundation of China-US relations”.

Ms Pelosi arrived in Taipei late on Tuesday on an unannounced but closely watched trip, saying that it showed unwavering US commitment to the self-ruled island that Beijing says is part of China.

On Wednesday, she thanked President Tsai Ing-wen for her leadership and called for increased inter-parliamentary co-operation.

“We commend Taiwan for being one of the freest societies in the world,” Ms Pelosi told Taiwan’s parliament.

She called her visit an “unequivocal statement” that the US stood with the democratic island and said new US laws aimed at strengthening the American chip industry to compete with China “offers greater opportunity for US-Taiwan economic co-operation”.

At her meeting with Ms Tsai – the first in person between the pair – Ms Pelosi was awarded one of Taiwan’s most important medals.

“Speaker Pelosi is truly one of Taiwan’s most devoted friends,” Ms Tsai said.

“We are truly grateful to you for making this visit to Taiwan to showcase the US Congress’s staunch support for Taiwan,” she said.

Ms Pelosi is not the first House Speaker to go to Taiwan – Newt Gingrich visited in 1997 – but her visit came as relations between Beijing and Washington deteriorate, and with China a much more powerful economic, military and geopolitical force than it was a quarter century ago.

Pressed on the visit on Wednesday, Prime Minister Anthony Albanese said Australia would continue to work with its allies to promote stability in the region. He said Australia’s position on Taiwan and China had not changed.

“We don’t want to see any unilateral change to the status quo,” he said.

“We’ll continue to work with partners to promote peace and stability across the Taiwan Strait.”

China considers Taiwan part of its territory and has never renounced using force to bring it under its control. The US warned China against using the visit as a pretext for military action against Taiwan.

Early on Wednesday, China’s customs department announced a suspension of imports of citrus fruits, chilled white striped hairtail and frozen horse mackerel from Taiwan, while its commerce ministry suspended export of natural sand to Taiwan.

A long-time China critic, especially on human rights, Ms Pelosi was to meet later on Wednesday with a former Tiananman activist, a Hong Kong bookseller who had been detained by China and a Taiwanese activist recently released by China, people familiar with the matter said.

Shortly after her arrival, China’s military announced joint air and sea drills near Taiwan and test launches of conventional missiles in the sea east of Taiwan, with Chinese state news agency Xinhua describing live-fire drills and other exercises around Taiwan from Thursday to Sunday.

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Before Ms Pelosi’s arrival on Tuesday, Chinese warplanes buzzed the line dividing the Taiwan Strait. The Chinese military said it was on high alert and would launch “targeted military operations” in response to Ms Pelosi’s visit.

White House national security spokesman John Kirby said on Tuesday after Ms Pelosi’s arrival that the US was not going to be intimidated by China’s threats or bellicose rhetoric and there was no reason her visit should precipitate a crisis or conflict.

“We will continue to support Taiwan, defend a free and open Indo-Pacific and seek to maintain communication with Beijing,” Mr Kirby told a later White House briefing, adding the US “will not engage in sabre-rattling”.

Mr Kirby said China might engage in “economic coercion” toward Taiwan, adding that the impact on American-Chinese relations will depend on Beijing’s actions in the coming days and weeks.

The US has no official diplomatic relations with Taiwan but is bound by American law to provide it with the means to defend itself.

China views visits by US officials to Taiwan as sending an encouraging signal to the pro-independence camp on the island. Taiwan rejects China’s sovereignty claims, saying only the Taiwanese people can decide the island’s future.

Taiwan’s defence ministry said 21 Chinese aircraft entered its air defence identification zone on Tuesday, and that China was attempting to threaten key ports and cities with drills around the island.

-with AAP