China is firmly opposed to any visit by the leader of the Taiwan authorities to the United States on any pretext and the US' violation of the one-China principle by having any form of contact with the region's authorities, officials said on Wednesday.

China will take countermeasures if the island's leader Tsai Ing-wen meets with US House Speaker Kevin McCarthy, they said.

Tsai is reportedly scheduled to visit some Central American nations from Wednesday to April 7, during which she plans to "transit" through the US and meet with McCarthy.

China has repeatedly made solemn representations to the US over Tsai's so-called "transit" through the US, said Foreign Ministry spokeswoman Mao Ning in response to a question at a news conference in Beijing.

"Past mistakes do not justify new ones, and the repetition of these mistakes does not make them legitimate," Mao said, adding that the "transit" plan is a cover for the Taiwan leader's attempt to seek "breakthroughs" for "Taiwan independence".

The spokeswoman rejected remarks that China is overreacting on the issue, and said it is the US that keeps conniving with and supporting "Taiwan independence" separatist forces.

"It is not China, but the US and 'Taiwan independence' separatist forces that are creating problems or making provocations," she said, urging the US to abide by the one-China principle and the three China-US joint communiques.

Mao said the US should deliver on its leaders' commitment to stopping all forms of official interaction with Taiwan and not supporting "Taiwan independence", "two Chinas" or "one China, one Taiwan".

The US should stop upgrading its substantive exchanges with Taiwan, as well as acts that obscure and hollow out the one-China principle. In addition, the US should not keep calling for "guardrails" for China-US relations on the one hand, but on the other hand, engage in dangerous acts that undermine the political foundation of bilateral ties, Mao said.

"China will closely follow the latest developments and resolutely safeguard its sovereignty and territorial integrity," she said.

Zhu Fenglian, a spokeswoman for the Taiwan Affairs Office of the State Council, said that should a meeting between Tsai and McCarthy take place during the so-called "transit", it will be another provocation that seriously violates the one-China principle, undermines China's sovereignty and territorial integrity, and damages the peace and stability across the Taiwan Straits.

"China firmly opposes this and will resolutely respond with countermeasures," Zhu said.

The "transit" by the Taiwan leader is in essence part of provocative efforts to "seek independence by relying on the US" and is also an attempt to create "one China, one Taiwan", "two Chinas" and other forms that violate the one-China principle, she said.

"Tsai plans to find opportunities to peddle the idea of 'Taiwan independence' in the international community and seek support from anti-China forces in the US," Zhu said.

The Taiwan leader will not only just stay at the airport or a hotel during her "transit" but also wants to contact US government officials and members of the US Congress under various pretexts to seek "official exchanges" between the US and the region, and collude with external anti-China forces, Zhu said. "We urge the US to refrain from arranging Tsai's 'transit' visit, bar any contact between her and US officials and take concrete actions to honor its solemn commitment of not supporting 'Taiwan independence'."

People from a range of parties and groups protested in Taipei against Tsai's so-called "transit" through the US, and condemned Tsai and the Democratic Progressive Party for their attempts to collude with the US to undermine the island.

The protesters said Tsai knows that seeking "Taiwan independence" is a suicidal path and yet she deceives the people into following that path. She is fully aware that the US is the world's biggest warmonger, which is sabotaging world peace, but she is still pushing the people of Taiwan toward the edge of an abyss, they said.

Tsai's "transit" through the US is bound to have a serious negative impact on the situation across the Taiwan Straits. Her administration and the DPP follow the US' orders, fully cooperate with US politicians' plans to destroy Taiwan and compromise the safety of the Taiwan people, the protesters said.

Taiwan currently faces a severe shortage of water and eggs, and is grappling with rising electricity prices, but Tsai and the DPP continue to neglect the sufferings of the people and seek their own gains, they added.