BEIJING—China tightened access to Tiananmen Square in central Beijing on Sunday, the anniversary of the military suppression of 1989 pro-democracy protests that left a still unknown number of people dead and discussions and commemorations forbidden within the country.

In Hong Kong, which had been the last Chinese-controlled territory to hold commemorations, eight people, including activists and artists, were detained on the eve of the anniversary of the crackdown, a move that underscored the city’s shrinking room for freedom of expression. Another 16 or more people were detained around Victoria Park on Sunday.

The large public space with its lawns and sports grounds used to be the scene of an annual candlelight gathering to remember the hundreds or thousands killed when army tanks and infantry descended on central Beijing on the night of June 3 and into the morning of June 4, 1989.

Discussion of the seven weeks of student-led protests that attracted workers and artists and their violent resolution has long been suppressed in China. It also became increasingly off-limits in Hong Kong since a sweeping national security law was imposed in June 2020, effectively barring anyone from holding memorial events.

The death toll from the 1989 violence remains unknown and the Communist Party relentlessly harasses those at home or overseas who seek to keep the memory of the events alive.

In Beijing, additional security was seen around Tiananmen Square, which has long been ringed with security checks requiring those entering to show identification. People passing by foot or on bicycle on Changan Avenue running north of the square were also stopped and forced to show identification. Those with journalist visas in their passports were told they needed special permission to even approach the area.

Still, throngs of tourists were seen visiting the iconic site, with hundreds standing in line to enter the square.

Ahead of the anniversary, a group of mothers who lost their children in the Tiananmen crackdown sought redress and issued a statement renewing their call for “truth, compensation, and accountability.”

Human Rights Watch called on the Chinese regime to acknowledge responsibility for the killing of pro-democracy protesters.

The Chinese regime “continues to evade accountability for the decades-old Tiananmen Massacre, which has emboldened its arbitrary detention of millions, its severe censorship and surveillance, and its efforts to undermine rights internationally,” Yaqiu Wang, senior China researcher at Human Rights Watch, said in a statement.

While Hong Kong, a former British colony handed over to Chinese rule in 1997, uses colonial-era anti-sedition laws to crack down on dissent, the persistence of non-conforming voices “lays bare the futility of the authorities’ attempts to enforce silence and obedience,” Amnesty International said.