A Chinese mainland Taiwan affairs spokeswoman condemned on Wednesday a series of recent actions by the United States to strengthen its exchanges with the island.

Zhu Fenglian, a spokeswoman for the Taiwan Affairs Office of the State Council, said under the complex and difficult situation in the Taiwan Straits, the US, with sinister intentions, was continuing to send wrong signals to "Taiwan independence "forces.

"It fuels the separatist activities for 'independence' and brings burdens and disasters to the people on the island. In the end, it will only be Taiwan that suffers the most," she said.

A large-scale People's Liberation Army exercise was conducted near the island last week after an agreement was reached between the American Institute in Taiwan and the Taipei Economic and Cultural Representative Office in the US.

The two sides signed a memorandum of understanding to establish a Coast Guard Working Group on March 25, the representative office said in a news release posted on its website on Friday.

On Friday, 20 PLA aircraft entered Taiwan's self-proclaimed southwest air defense identification zone, the most in one day since the PLA started routine exercises in the region last year, the island's defense authority said.

Zhu said Taiwan is a part of Chinese territory and the PLA is fully justified in carrying out exercises and training activities to safeguard national sovereignty and territorial integrity.

She voiced opposition to official exchanges in any form between the US and Taiwan after the US ambassador to Palau joined a delegation led by Palau's president that visited Taiwan on Sunday.

US lawmakers put forward the Taiwan Relations Reinforcement Act last week, which seeks to update US policy toward Taiwan. If passed, it would update the status of the head of the AIT to the level of "ambassador".

Zhu urged the US to abide by the one-China principle and stipulations in the three Sino-US joint communiques.

She also condemned Taiwan's ruling Democratic Progressive Party for relying on the US to seek independence and said it will fail.

Bao Chengke, a professor of cross-Straits relations at the Institute for East Asian Studies in Shanghai, said the Biden administration was continuing to play the "Taiwan card" to challenge Beijing.

The US is trying to move beyond the one-China framework by upgrading Taiwan's status, including allowing US officials to visit Taiwan, he said.

"The mainland's attitude is firm and clear," Bao said. "The military aircraft exercise near the island is sending a warning to the island authorities and shows national sovereignty. If necessary, more measures should be taken to make it clear that Taiwan is a part of China."