Taiwan called on China to atone for the 1989 Tiananmen crackdown on Thursday, as the island marked the anniversary of the day student-led protests were violently crushed by tanks with small vigils of its own.

Hundreds of people were killed during the Communist Party's suppression of demonstrations calling for democratic reforms.

Open discussion of the incident is forbidden on the Chinese mainland, with censors scrubbing mentions of protests, and dissidents often visited by police in the days leading up to the June 4 anniversary.

"Around the world, there are 365 days in a year. Yet in China, one of those days is purposely forgotten each year," Taiwan's President Tsai Ing-wen said on Twitter.

Tsai said Beijing needed to confront the legacy of the incident, just as Taiwan had been forced to reckon with its own authoritarian past before its transition to democracy in the 1990s.

"There were once days missing from our calendar, but we've worked to bring them to light. I hope one day China can say the same," she wrote.

Hundreds gathered in Taipei on Tuesday for a candlelight vigil to mourn the Tiananmen dead, according to organisers.

Some of those in the crowd were Hong Kongers who have relocated to the island following last year's tumultuous pro-democracy protests which were fuelled by years of rising fears that Beijing was stamping out the city's freedoms.

Hundreds attended an evening vigil in Taipei
Hundreds attended an evening vigil in Taipei AFP / Sam Yeh

"We can freely and safely express our thoughts on June 4 in Taiwan and demand redress," Judith Ng, 47, told AFP, near a banner reading: "Free Hong Kong, revolution of our times".

Ng said she moved to Taiwan in December with her teenage son who took parts in protests.

"We will never forget June 4 and we will never give up fighting for Hong Kong's democracy," added Edith Chung, another Hong Kong immigrant and organiser of the vigil.

Taiwanese have closely followed the unrest in neighbouring Hong Kong.

Beijing regards Taiwan as its own territory and has vowed to one day seize it, by force if necessary. It has proposed a "one country, two systems" model similar to how it runs Hong Kong.

But Taiwanese have widely rejected the proposal, a sentiment that has only increased as police crack down on protests in Hong Kong.

"I hope the truth about June 4 will be unveiled and I also want to show support for Hong Kong," Taiwanese lawyer Zoe Lee, 24, told AFP after joining the annual Tiananmen vigil for the first time.

On Wednesday Taiwan's Mainland Affairs Council called on Beijing to offer "sincere apologies" over the Tiananmen crackdown.

China's foreign affairs ministry derided the comments, which spokesman Zhao Lijian described as as "complete nonsense" on Wednesday.

Tensions between Taipei and Beijing have surged since Tsai was elected in 2016 because her government considers the island to be a de facto independent state rather than an part of China.

She has pledged humanitarian assistance for Hong Kongers after Beijing's parliament approved plans outlining a new national security law for the city.