US House Speaker Kevin McCarthy said on Tuesday he will meet Taiwan President Tsai Ing-wen in California, but did not rule out a possible visit to the self-governed island.

Tsai's government had provided McCarthy's staff with intelligence that a high-profile US visit could provoke a Chinese threat, the Financial Times reported earlier on Tuesday, citing an unidentified senior Taiwanese official.

The FT added that the speaker would scrap a potential trip to Taiwan, and the meeting would instead take place in California.

McCarthy confirmed plans to meet Tsai in the United States, but told reporters in Washington the meeting does not preclude a trip to Taiwan.

"That has nothing to do with my travel, if I would go to Taiwan," McCarthy was quoted as saying by Bloomberg.

"China can't tell me where and when I can go."

A trip in August by McCarthy's predecessor Nancy Pelosi sparked condemnation from China, which responded with massive military drills around the island.

Taiwan lives under constant threat of an invasion by China, which views the democratically ruled island as part of its territory to be seized one day, by force if necessary.

The United States is one of Taiwan's closest allies and biggest arms suppliers but also adopts a "One China" policy, recognizing Beijing diplomatically and opposing any unilateral changes to the status quo from either side.

Beijing was "gravely concerned" by the news of Tsai and McCarthy's planned meeting, said foreign ministry spokesperson Mao Ning, at a daily press briefing.

"We have lodged stern representations with the US side and demanded clarification from them," he added.

"I want to stress that China firmly opposes any form of official contact between the US and Taiwan, firmly opposes the ringleaders of the Taiwan independence separatists scurrying off to the United States in any name and under any pretext, and firmly opposes the US violations of the One China principle and its engagement in any form of contact with Taiwan independence separatists."

Taiwanese Defense Minister Chiu Kuo-cheng said on Monday a sharp increase in Chinese military spending announced at the weekend was potentially aimed at the island.

"I think they are waiting for a good reason to send troops, such as high-level visits from other countries to Taiwan or too-frequent activities between our military and other countries," Chiu said.

Tsai's office offered no confirmation about traveling to the United States when approached by AFP on Wednesday, saying the president's schedule was still being finalized.

She was last in the United States in 2019, stopping over while making official visits to diplomatic allies in the Caribbean.

AFP