The reduced number followed a boycott of the event by university student unions for a second consecutive year amid rising localist sentiment in the city.

All six soccer pitches in the park were filled. Late arrivals were accommodated on an adjacent lawn.

Officers remained on alert after the vigil as radicals from the League of Social Democrats, People Power and Demosisto said they planned to march to Beijing’s liaison office in Western.

A sorrowful atmosphere ­settled over the park throughout the two-hour vigil, which started with a wreath-laying ceremony in front of a replica of the Monument to the People’s Heroes in ­Tian­anmen Square.

Participants, mostly wearing black, sang patriotic songs and chanted slogans, demanding ­Beijing reverse its verdict on the pro-democracy movement that it labelled a “counter-revolutionary rebellion”.

In a pre-taped video address, a member of the Tiananmen Mothers group, Ge Guirong, 83, whose son Du Guangxue was killed in the 1989 crackdown, thanked Hongkongers for their support over the past 28 years. “As a mother, it is unacceptable for the government to escape its responsibility for the massacre under the cover of ‘a political storm’ ... I hope the issue of June 4 can be solved fairly and justly,” she said.

Delivering the eulogy, alliance vice-chairwoman Chow Hang-tung said people in Hong Kong were lucky because they would not be jailed or persecuted for mourning those who died in the crackdown. “Accompanying such luck is our unshirkable responsibility – to take further steps to speak out for those unable to speak out, to pay tribute to the victims for those who are prevented from doing so, and to offer comfort to those still alive,” she said.

One participant, Cheung Ka-chai, a 20 year-old university ­student, joined the vigil alone ­because his family backs the government while his friends support Hong Kong independence.

“They’re anti-Chinese and pro-Hong Kong independence. They think it’s not about us. But culturally we’re closely related, and geographically so close to each other,” he said.

Earlier Sunday in Beijing, the authorities allowed seven members of the Tiananmen Mothers to sweep the graves of their loved ones in Wanan public cemetery on the capital’s western outskirts.

US Secretary of State Rex Tillerson called on the central government to make “a full accounting of those killed, detained, or missing due to the events of June 4, 1989”.

“We urge China to cease harassment of family members seeking redress and to release from prison those who have been jailed for striving to keep the memory of Tiananmen Square alive.”

Additional reporting by Stuart Lau in Beijing