As Beijing steps up efforts to silence dissenting voices ahead of the 25th anniversary of the Tiananmen Square crackdown, organisers of the annual candlelight vigil in Victoria Park are expecting a record turnout.
The Hong Kong Alliance in Support of Patriotic Democratic Movements in China says it is "confident" more than 150,000 will attend and are preparing for the park to be "fully carpeted".
"It is important for us Hong Kong people to show up this year," said the alliance chairman and Labour Party legislator Lee Cheuk-yan.
"We see that Beijing is doing whatever it can to silence whoever dares to publicly remember the massacre. We in Hong Kong have the responsibility to speak for those who are kept silent in China.
"We in Hong Kong must fight the Communist Party's attempt to airbrush the event from the history."
Turnout estimates for past vigils vary. Last year's event, cut short by bad weather, was attended by 150,000 according to the alliance; 54,000 according to police. In 2009, the 20th anniversary was attended by 200,000 according to the alliance; 65,000 according to police.
Last year, some latecomers complained of not being able to hear events on the main stage, but the alliance says audio equipment will be set up to make sure events can be followed from all corners of the park.
Hong Kong is the only place on Chinese soil where large scale events to commemorate the June 4 crackdown are held.
As the 25th anniversary approaches, Beijing has ramped up efforts to silence dissenting voices and the families of those killed in the 1989 crackdown.
The human rights lawyer Pu Zhiqiang and the prominent journalist Gao Yu have both been detained, while Ding Zilin , a founder of Tiananmen Mothers, which represents families of those killed, has been placed under house arrest.
"The Communist Party does not want the people to remember because the party fears to face the truth," said Lee. "If the party thinks it is right, it should celebrate the crackdown."
Voice of Loving Hong Kong is planning a rally outside Victoria Park on the evening of June 4 in support of the crackdown. Chairman Patrick Ko Tat-pun said the military action was needed to "maintain national security and restore social order".
Two pan-democratic groups - Proletariat Political Institute and Passion Times - will host an alternative rally in Tsim Sha Tsui also on the evening of June 4. Some 3,000 people are expected. The groups say the alliance's event in Victoria Park has become too "ceremonial".