Democracy protesters took part in the largest mass rally through Hong Kong's streets in months on Sunday in a forceful display of support for the movement, with a leading activist warning the city's pro-Beijing leaders they had a "last chance" to end the political crisis.

Organisers estimated some 800,000 people snaked for hours through the financial hub's main island as the protests marked six months, a vivid illustration of the hostility that still seethes towards the government after half a year of unrest.

Millions of Hong Kongers have hit the streets in protests fuelled by years of growing fears that authoritarian China is stamping out the city's liberties
Millions of Hong Kongers have hit the streets in protests fuelled by years of growing fears that authoritarian China is stamping out the city's liberties AFP / DALE DE LA REY

The city's police force, which historically gives lower crowd turnout figures, told local media 183,000 people attended at the peak, still one of their highest estimates in months.

The rally received rare police permission and came two weeks after pro-establishment parties got a drubbing in local elections, shattering government claims that a "silent majority" opposed the protests.

As night fell the crowds switched on their mobile phone torches, creating a glittering carpet of lights that stretched far into the distance, their chants bouncing off the towering skyscrapers above.

Activists say anger is building once more after chief executive Carrie Lam ruled out any further concessions despite pro-democracy candidates winning a landslide in local council elections
Activists say anger is building once more after chief executive Carrie Lam ruled out any further concessions despite pro-democracy candidates winning a landslide in local council elections AFP / DALE DE LA REY

Many of the black-clad attendees voiced anger and frustration that chief executive Carrie Lam and Beijing have ruled out any further concessions despite the landslide election defeat.

"No matter how we express our views, through peacefully marching, through civilised elections, the government won't listen," said a 50-year-old protester, who gave his surname Wong. "It only follows orders from the Chinese Communist Party."

Sunday afternoon's march will follow a well-worn route on the main island from Victoria Park to the heart of the commercial district
Sunday afternoon's march will follow a well-worn route on the main island from Victoria Park to the heart of the commercial district AFP / Anthony WALLACE

"I don't know how long the fight will be," added another protester, who gave his first name as Kelvin. "So far I can't see the end but we won't back down."

Cantonese popstar Denise Ho, whose music is blacklisted on the Chinese mainland, tweeted a video of the huge crowds with the caption: "Here's your majority Carrie Lam".

Over the last two days the city's new police chief Chris Tang has been in Beijing where he met with senior party figures
Over the last two days the city's new police chief Chris Tang has been in Beijing where he met with senior party figures AFP / GREG BAKER

Semi-autonomous Hong Kong has been battered by increasingly violent demonstrations in the starkest challenge the city has presented to Beijing since its 1997 handover from Britain.

Hong Kong residents give their take on Hong Kong's pro-democracy demonstrations six months on.The unprecedented movement was born on June 9, when an estimated million people took to the streets to protest a proposed bill allowing extradition to mainland
Hong Kong residents give their take on Hong Kong's pro-democracy demonstrations six months on.The unprecedented movement was born on June 9, when an estimated million people took to the streets to protest a proposed bill allowing extradition to mainland China. AFPTV / Vanesse Chan

Millions have marched in protests fuelled by years of growing fears that authoritarian China is stamping out the city's liberties.

The last fortnight has seen a marked drop in violence and vandalism after the landslide win by pro-democracy candidates.

Police took the unusual step of allowing the Civil Human Rights Front (CHRF) to hold Sunday's march -- the first time the group has been granted permission since mid-August -- but they warned they would have zero tolerance for violence by radicals.

Over the last two days the city's new police chief Chris Tang has been in Beijing where he met with senior party figures
Over the last two days the city's new police chief Chris Tang has been in Beijing where he met with senior party figures AFP / GREG BAKER

The movement's demands include an independent inquiry into the police's handling of the protests, an amnesty for those arrested, and fully free elections.

"Carrie Lam should listen to the demands of Hong Kongers as soon as possible," CHRF's leader Jimmy Sham told reporters after earlier billing the march as Lam's "last chance" to listen to the people.

The protests were initially sparked by a now-abandoned attempt to allow extraditions to the mainland but have since morphed into a popular revolt against Beijing's rule.

The CHRF, which advocates non-violence, has been the main umbrella group behind record-breaking rallies earlier in the summer that saw huge crowds regularly march in searing heat.

One march in June drew what organisers said was a million people, another soon after drew double that.

Authorities have repeatedly banned major rallies in recent months citing the risk of violence from hardcore protesters.

Large crowds have simply ignored the bans, sparking near-weekly tear gas and petrol bomb clashes that have upended Hong Kong's reputation for stability and helped tip the city into recession.

Hours before the march was due to start, police displayed weapons, including a pistol and knives, they said had been found during overnight raids where eleven people were arrested.

Monday marks the six-month anniversary of the protests during which some 6,000 people have been arrested and hundreds injured, including police.

Online forums used to organise the movement's more radical wing have vowed to target Monday's morning commute if there is no response from Lam.

Years of huge, peaceful democracy marches have made little headway, leading to increased radicalisation among some Hong Kong protesters and a greater willingness to embrace violent tactics.

Since the local elections the city's chief executive has remained steadfast in her opposition to further concessions and Beijing has stuck by her even as she languishes with record low approval ratings.