Taiwan's Foreign Ministry officials welcome US Representatives at Taipei Songshan Airport in Taipei, Taiwan. Reuters

The unannounced two-day trip came after Beijing sent warships, missiles and jets into the waters and skies around Taiwan, a self-ruled democracy that China's leaders claim and have vowed to one day seize.

The five-member congressional delegation — led by Senator Ed Markey of Massachusetts — was due to hold a meeting with President Tsai Ing-wen on Monday morning followed by a banquet at the foreign ministry.

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Their visit will focus on trade, regional security and climate change, Washington's de facto embassy in Taipei said.

Taiwan's foreign ministry hailed the visit as another sign of a friendship between Taipei and Washington "that is not afraid of China's threats and intimidation".

But the bipartisan trip sparked another caustic response from Beijing, which has drawn down its drills but pressed on with military patrols in the Taiwan Strait.

State news agency Xinhua published a commentary after the lawmakers' arrival Sunday with the headline 'US politicians should stop playing with fire on Taiwan question'.

It called the visiting American lawmakers opportunists thinking about their own political interests as November's midterm elections draw near.

"Those US politicians who are playing with fire on the Taiwan question should drop their wishful thinking," the agency said.

"There is no room for compromise or concessions when it comes to China's core interests," it said.

Agence France-Presse