A Chinese mainland spokesman denounced Taiwan's Democratic Progressive Party authorities on Wednesday for colluding with anti-China forces on "independence" following Taiwan leader Tsai Ing-wen's remarks at a meeting on Tuesday.

In a speech to the "11th Global Assembly of the World Movement for Democracy" in Taipei, the head of the DPP said that the people of Taiwan have never shied away from challenges from the mainland.

Ma Xiaoguang, a spokesman for the Taiwan Affairs Office of the State Council, said at a news conference in Beijing that "the so-called assembly is nothing but a farce".

DPP authorities have been suppressing opponents on the island and deceiving the international community, he said. "How dare they talk about democracy?"

Ma added that DPP authorities are doomed to fail by colluding with anti-China forces for "independence" under the guise of "democracy", inciting cross-Straits confrontation and engaging in secessionist acts.

"The Taiwan question is China's internal affair, which tolerates no interference from outside forces," Ma said.

The root cause of the current tension in the Taiwan Straits is due to the DPP authorities' stubborn adherence to the secessionist stance of "Taiwan independence "and engagement with external forces for provocation against the mainland, while external forces play the "Taiwan card" and use the island to contain the mainland, Ma said.

He urged the US to fulfill its political commitment to not support "Taiwan independence" and stop sending wrong signals to "Taiwan independence" forces.

Language resolutely opposing and deterring separatists who seek "Taiwan independence" was added to the Constitution of the Communist Party of China at the 20th CPC National Congress, which concluded on Saturday.

"'Taiwan independence' is the biggest obstacle to the reunification of the motherland and a serious danger to national rejuvenation," Ma said.

The addition to the Party Constitution was made in response to the current cross-Straits situation and reflects the will of the Party and the wishes of the people, he said.