United States Speaker Nancy Pelosi should have canceled her planned visit to Taiwan rather than delay it, an official said Wednesday, warning that resolute countermeasures will be taken against acts that seriously undermine China's sovereignty and territorial integrity.

Ma Xiaoguang, a spokesman for the Taiwan Affairs Office of the State Council, made the remarks at a news conference in Beijing during comments about the island's Democratic Progressive Party authority's invitation.

Taiwan media reported earlier last week that Pelosi was scheduled to lead a delegation that was due to arrive in Taiwan on Sunday, which would have made her the first sitting US House speaker to visit since 1997.

However, the trip was postponed when she tested positive for COVID-19 on Thursday, and followed protests from Beijing officials.

Pelosi announced on Monday that she has tested negative for COVID-19 and will end isolation on Tuesday, and the DPP authority has been working actively on the invitation.

Ma called on the US to abide by the one-China policy and the stipulations of the three China-US Joint Communiques.

He said that the US should fulfill its commitment to China on the Taiwan question, stop playing the Taiwan card and stop using the Taiwan question to contain China.

He also urged the DPP authority to stop its provocative attempts to collude with foreign forces on independence.