Measures will be taken to counter the collusion between the United States and Taiwan, a mainland spokeswoman said on Monday, after the ruling Democratic Progressive Party of Taiwan welcomed the move lifting restrictions governing US official contacts with the island.

US Secretary of State Mike Pompeo announced on Saturday that he was lifting what he called "self-imposed" restrictions on contacts between US officials and those on Taiwan, which comes less than two weeks before President-elect Joe Biden is set to take office.

The Taipei Economic and Cultural Representative Office in the US said the move showed the "strength and depth" of the US-Taiwan relationship. The island's "foreign affairs" head Joseph Wu also expressed gratitude toward Pompeo and the US Department of State for the move.

Zhu Fenglian, a spokeswoman for the Taiwan Affairs Office of the State Council, said the mainland has repeatedly reiterated firm opposition to official exchanges between the US and the Taiwan region of China.

The one-China principle is the political foundation and fundamental prerequisite for the establishment of diplomatic relations between China and the US. It is a commitment made by the US government to abide by the one-China principle and the provisions of the three China-US joint communiques, she said.

"Any violation of this commitment seriously violates the basic norms governing international relations and is illegal and invalid," Zhu said.

"The DPP administration is acting as the pawn of foreign forces and relying on the US to seek independence, which will only bring serious disaster to the people of the island," she said.

The mainland will take resolute and forceful measures to counter any collusion between the US and the island, she added.