HONG KONG - Unrest in Hong Kong shows no signs of abating as more protests kicked off for the 17th straight weekend, in the lead-up to the 70th anniversary of the founding of the People's Republic of China on Tuesday (Oct 1).

Thousands gathered at Tamar Park in the government headquarters compound for a Saturday rally that was cut short and organised by the Civil Human Rights Front. But some demonstrators started spraying graffiti on building shutters shortly after the rally started at 7pm, after police used pepper spray to disperse a group that crowded near one part of the water barricades.

A group of protesters then took over main thoroughfare Harcourt Road, near Tamar Park, threw petrol bombs, pelted rocks and broke some windows on the second floor. They also tried to open some metal gates surrounding the building.

Water cannon was deployed before riot police emerged from the government offices to clear the streets and protesters dispersed quickly.

The Front is the organiser behind some of the biggest protests Hong Kong has had since the handover in 1997, including the two-million strong march on June 16.

Earlier in the day, thousands gathered from 4pm in several locations from Victoria Park in Causeway Bay all the way to the government headquarters in Admiralty and put up Post-it notes and posters in their attempt to rebuild "Lennon Walls", some of which were torn down by pro-Beijing activists last weekend.

Besides the continued calls for Chief Executive Carrie Lam and her administration to give in to protesters' five demands, the Saturday rally marked the fifth anniversary of the 2014 Umbrella Movement.

The movement then had ultimately failed to win democratic elections - now one of the five key demands of protesters - for the city's leader by the time it was forced to disperse 79 days later.

In response to calls for universal suffrage at the Saturday rally, the government said the "'one person, one vote' for selecting the Chief Executive and electing all members of the Legislative Council is enshrined as an ultimate aim in the Basic Law" of the territory.

"To achieve this aim, the community needs to engage in dialogues, premised on the legal basis and under a peaceful atmosphere with mutual trust, with a view to narrowing differences and attaining a consensus agreeable to all sides.

"The Hong Kong government will assess the situation carefully and take forward constitutional development in accordance with the Basic Law and the relevant Interpretation and Decisions of the Standing Committee of the National People's Congress," the government said.

The other four conditions protesters in the current anti-government movement want fulfilled are: complete withdrawal of the extradition Bill; the release of all protesters arrested; removing the label of protests as "riot"; and an independent judge-led inquiry into allegations of police brutality.

On Sept 4, three months after the escalation of protests began, Mrs Lam announced that the controversial extradition Bill will be withdrawn completely, but protesters and pan-democratic lawmakers have rejected her olive branch.

On Thursday, Mrs Lam held an unprecedented dialogue with about 130 individuals, while hundreds protested outside the venue. She had previously promised such dialogue to reconnect with society and to defuse public anger.

At the session, Mrs Lam admitted to a "disconnect" between Hong Kongers and the government and vowed to rebuild the trust. But she reiterated that not all of the five demands can be met as those who broke the law have to pay the price.

The city is on edge as the anniversary of the founding of modern China draws near and more protests and events have been planned from Saturday through to Oct 1.

Besides Saturday's march and rally, there is a Global Anti-Totalitarianism march on Sunday at 2.30pm from Sogo mall in Causeway Bay with solidarity events planned in other cities, and a planned strike on Monday.

On Oct 1, some groups plan to jam up the transport network to the airport in the morning.

In one of the polls conducted on chat app Telegram, more than half of the 12,000 surveyed voted to march on Oct 1 afternoon in Hong Kong island before regrouping in other locations including Tsuen Wan, Sha Tin and Wong Tai Sin.

The Front's proposed Oct 1 march from Victoria Park to Chater Garden, as well as a rally, were rejected by the police on Friday due to threats of violence.

In a letter sent to the Front on Friday, the police said the rally is near "high-risk" facilities like government headquarters or MTR stations, where violent clashes are likely. The Front is appealing against the decision.

On Friday night, thousands of people gathered in Edinburgh Place to voice their concerns over detained protesters sent to San Uk Ling holding centre.

The calls came even though Mrs Lam and the police announced during her dialogue session that the facility will no longer be used to house detained demonstrators.

The facility is in Sheung Shui, close to the border with the mainland, and has been the target of many allegations that police have abused anti-government protesters sent there, including denying them medical treatment and access to lawyers.

So far, police say they have detained almost 1,600 protesters.

In a briefing on Friday, they said they have arrested 550 people since school resumed on Sept 1. Of these, 38 per cent are secondary and university students. In the period before Sept 1, about 25 per cent of all arrested protesters were students.

The police have described this as "an alarming trend", adding that "it's worrying to see these youths breaking the law and possibly having criminal records at such a young and tender age".

On Friday, Secretary for Education Kevin Yeung Yun Hung also urged in a letter to school principals, teachers and parents to remind students not to take part in "potentially chaotic and dangerous" protests this weekend and on National Day on Oct 1.