Nancy Pelosi arrived in Taiwan

Taiwan's president struck a defiant tone Wednesday as she hosted US House Speaker Nancy Pelosi, with a furious China gearing up for military exercises dangerously close to the island's shores in retaliation for the visit.

Pelosi landed in Taiwan on Tuesday despite a series of increasingly stark threats from Beijing, which views the island as its territory and had said it would consider the visit a major provocation.

China responded swiftly, warning the US ambassador in Beijing of "extremely serious consequences" and announcing military drills around Taiwan.

"Facing deliberately heightened military threats, Taiwan will not back down. We will... continue to hold the line of defence for democracy," Taiwanese President Tsai Ing-wen said at an event with Pelosi in Taipei.

She also thanked Pelosi for "taking concrete actions to show your staunch support for Taiwan at this critical moment".

China tries to keep Taiwan isolated on the world stage and opposes countries having official exchanges with Taipei.

Pelosi, second in line to the presidency, is the highest-profile elected US official to visit Taiwan in 25 years.

"Today, our delegation... came to Taiwan to make unequivocally clear we will not abandon our commitment to Taiwan," she said at the event with Tsai.

Earlier, Pelosi said her group had come "in friendship to Taiwan" and "in peace to the region".