BEIJING — Chinese authorities are snuffing out any remembrance of the deadly 1989 military crackdown on student-led pro-democracy protests in Tiananmen Square, which happened 37 years ago Thursday, in a further tightening of a yearslong campaign to erase what happened from public memory.

Police told relatives of the victims they would not be allowed to visit a cemetery in Beijing on the anniversary of the crackdown, a person with knowledge of the matter said. The person spoke on condition of anonymity because of fear of retribution.

Relatives of the victims visited the cemetery on the anniversary for more than 30 years to read memorial statements with police keeping watch, Amnesty International said. They belong to a group called Tiananmen Mothers.

Hundreds of people, and possibly thousands, were killed in 1989 as troops advanced through crowds that were trying to stop the military from reaching the protesters in Tiananmen Square, a vast plaza in the center of the Chinese capital. The decision by the Communist Party leadership to send in the military was a pivotal moment in China’s modern history, determining that the market reform that transformed the country into the world’s second largest economy would not be coupled with political liberalization.

In Hong Kong, police stepped up security Thursday to prevent any kind of commemoration at or near a park where a massive candlelight vigil lit up the night on the anniversary every year until a clampdown following major anti-government protests in 2019. On Wednesday, they stopped two performance artists from making symbolic gestures in separate incidents. One briefly held up a question-mark-shaped balloon outside a department store.

U.S. Secretary of State Marco Rubio, who recently accompanied President Donald Trump on a state visit to Beijing, issued a statement marking the anniversary. “No amount of censorship can erase the past,” it said. “Those who sacrificed to uphold their unalienable rights of free expression and peaceful assembly will be vindicated someday.”

Tiananmen Mothers issued an annual appeal for justice ahead of this year’s anniversary. The statement, signed by 107 people, demanded full disclosure of what happened, compensation for the victims and their families and the pursuit of legal accountability for those responsible.

“The sacrifice of our family members is an indelible pain etched in our hearts. Our tears have run dry, grief is buried deep within, what remains is eternal remembrance of our family members and hatred for the crime of massacring the people,” Zhang Xianling, a member of the group, said in a video message posted on Facebook — which is blocked in China.

Amnesty said it is deeply troubling that China’s suppression of the commemoration appears to be escalating. “Banning the relatives of people killed in the Tiananmen crackdown from visiting their loved ones’ graves is a heartless act by the Chinese authorities,” Sarah Brooks, the organization’s deputy director for Asia, said in a statement.

The Beijing Public Security Bureau did not respond to a faxed request for comment.

Authorities in Hong Kong have banned the vigil since 2020, at first citing the COVID-19 pandemic. Three of the organizers of the vigil have been charged under a 2020 national security law. One pleaded guilty, which may result in a lesser sentence. The other two have been tried and are awaiting a verdict.

One of them, lawyer Chow Hang-tung, said in an online post published last weekend that she would go on a 37-hour hunger strike in prison. “Behind the glitter of power and dictatorship lies the blood and broken dreams of ordinary people. For in amnesia lies the demise of democracy,” she wrote.

Derek Chu, a former district councilor, said on Instagram that he visited Chow on Thursday and told her he would also stop eating for 37 hours to show his support. He added that a shop he runs is giving out LED candles that can be used to remember the victims.

___

Leung reported from Hong Kong.