Three young Hong Kong dissidents including Joshua Wong were remanded into custody on Monday after pleading guilty to inciting a rally during last year's pro-democracy protests, deepening the crackdown against Beijing's critics.

Hong Kong was convulsed by seven straight months of huge and often violent democracy rallies last year in which millions took to the streets.

Wong, 24, was prosecuted alongside fellow activists Ivan Lam and Agnes Chow over a protest which took place last summer outside the city police headquarters.

"We will continue to fight for freedom -- and now is not the time for us to kowtow to Beijing and surrender," Wong told reporters on his way to court.

Wong is being prosecuted alongside two other well-known dissidents: Ivan Lam (C) and Agnes Chow (R) Wong is being prosecuted alongside two other well-known dissidents: Ivan Lam (C) and Agnes Chow (R) Photo: AFP / Peter PARKS

Once inside Wong pleaded guilty to inciting and organising an illegal assembly. Lam pleaded guilty to incitement while Chow, 23, admitted inciting and joining the protest.

All three were remanded into custody pending sentencing on December 2, meaning a jail term is all but guaranteed.

The maximum sentence a magistrate's court can hand down is three years.

"Everyone hang in there. I know it's tougher for you to remain out there," Wong shouted inside court.

Hong Kong was rocked by seven straight months of pro-democracy protests last year -- demonstrations which led to thousands of arrests Hong Kong was rocked by seven straight months of pro-democracy protests last year -- demonstrations which led to thousands of arrests Photo: AFP / Ye Aung THU

Small groups of supporters surrounded their prison van as they were driven away shouting "Add oil!" and "No rioters, only tyranny!"

Add oil is a popular phrase of encouragement in Cantonese while authorities dismissed both peaceful and violent protesters alike last year as rioters.

Wong and Lam were later filmed leaving a police van, handcuffed together, and entering a detention facility.

Prominent democracy dissident Joshua Wong announces he and two other leading activists will plead guilty at the opening of a trial over their involvement in last year's protests. Prominent democracy dissident Joshua Wong announces he and two other leading activists will plead guilty at the opening of a trial over their involvement in last year's protests. Photo: AFPTV / Celia CAZALE

Despite his youth, Wong has already spent time in prison for leading democracy protests and told reporters that he was ready to return.

"Emotionally I am reluctant in every way to be jailed but rationally I have absolutely no space to complain in comparison with many others," he said outside court, in a reference to the hundreds of protest-linked prosecutions already concluded.

Chow appeared less self-assured.

Profile of Hong Kong pro-democracy activist Joshua Wong Profile of Hong Kong pro-democracy activist Joshua Wong Photo: AFP / Janis LATVELS

"If sentenced, this will be my first time in prison," she wrote in a Facebook post on Sunday. "While I say I have mentally prepared for this, I am still a bit scared."

Wong became an activist when he was in his early teens, organising successful rallies in 2012 against plans to make Hong Kong's education system more "patriotic" and similar to the mainland.

In 2014 he and Chow helped inspire and lead the "Umbrella Movement" -- a 79-day peaceful occupation of three busy intersections by a largely student-led campaign calling for universal suffrage.

Wong was jailed for his involvement in those protests, alongside most of that movement's main leaders.

He was still in jail when last year's much larger democracy protests kicked off, though he made appearances at numerous rallies after his release.

However the protests were deliberately leaderless, mostly organised by social media and encrypted chat forums.

They were also much more violent. Riot police unleashed thousands of rounds of tear gas and rubber bullets and were frequently filmed using batons to beat arrested demonstrators.

Their headquarters was besieged on multiple occasions with crowds hurling eggs and daubing its walls with graffiti.

Small groups of hardline activists resorted to rocks, petrol bombs and even bows and arrows.

More than 10,000 people were arrested and most of Hong Kong's leading activists and opposition figures now face prosecution.

The demonstrations petered out at the start of the year thanks to fatigue, mass arrests and the emergence of the coronavirus.

An anti-pandemic ban on more than four people gathering in public has remained in place for most of this year.

Beijing has also imposed a broad security law which ramps up its direct control over the semi-autonomous city and outlaws certain political views.

Pro-democracy lawmakers have also been disqualified and local legislature elections delayed for a year.

Authorities say they have returned much-needed stability to the global trade hub.

Critics counter that opposition to Beijing's rule remains widespread despite the lack of street protests.