Tuesday marks 30 years since Chinese troops opened fire to end the student-led unrest in Beijing.

China continues to cover up the truth about the bloody crackdown on pro-democracy demonstrators in and around Tiananmen Square 30 years ago, Taiwan's president said on Tuesday, ahead of vigils in the region to commemorate the event.

Tuesday marks 30 years since Chinese troops opened fire to end the student-led unrest in Beijing.

Chinese authorities ban any public commemoration and have never released a full death toll. Estimates from human rights groups and witnesses range from several hundred to several thousand.

“The Chinese government not only did not plan to repent for the past mistake, but it also continued to cover up the truth,” Taiwan President Tsai Ing-wen said in a Facebook post.

Security officials stand guard as tourists take photos on Tiananmen Square in Beijing, Tuesday, June 4, 2019. Chinese authorities stepped up security Tuesday around Tiananmen Square in central Beijing, a reminder of the government's attempts to quash any memories of a bloody crackdown on pro-democracy protests 30 years ago. | Photo Credit: AP

“Please be reassured - Taiwan will definitely defend democracy and freedom. Regardless of threats and infiltration, as long as I'm the president, Taiwan would not bow to pressure,” she said.

The post, which was accompanied by a cartoon of Tsai holding a candle, also expressed concern for China's “erosion of freedom” in Hong Kong, which was returned to Chinese rule in 1997 under a “one country, two systems” formula.

Democratic Taiwan tends to use the Tiananmen Square anniversary to criticise China and call for it to face up to its actions. China claims self-ruled Taiwan as its sacred territory, to be taken back by force if necessary.

Ms. Tsai's comments came ahead of large candlelight vigils in the region, including in Taipei and Hong Kong, to commemorate the events of 1989 that remain a taboo subject in China.

Beijing has increased government suppression of rights activism, pushing the demonstrators' original goals further away than ever.

Financial information provider Refinitiv, under pressure from China's government, has removed from its Eikon terminal Reuters news stories related to the 30th anniversary of the Tiananmen crackdown.

Tsai's government urged Beijing on Monday to “sincerely repent” for the Tiananmen crackdown, while a Chinese newspaper said nobody in China was interested in dragging up the past.

China suspects Ms Tsai and her ruling party of pushing formal independence for Taiwan, a red line for China.