Hong Kong's justice chief insisted Wednesday that any prosecution of plainclothes officers who were filmed beating a handcuffed protester would be handled impartially, as fresh clashes broke out on the city's streets.
The accused officers were removed from their posts after the assault, which occurred early Wednesday when police swooped to clear newly erected barricades blocking a road near government headquarters in the city's Admiralty district.
Just 24 hours later a small contingent attempted to retake an underpass on the same road, leading to a confrontation that saw protesters pepper-sprayed and police heckled with chants accusing them of links with criminal triad gangs.
Crowds intermittently numbering in the tens of thousands have blocked main roads in three districts of the semi-autonomous Chinese city since September 28, protesting at what they call "fake democracy" offered by Beijing.
They are angered at China's insistence that it vet candidates standing for election as the city's next leader in 2017.
On a visit to London, Hong Kong's Secretary for Justice Rimsky Yuen said he had not seen the footage of the alleged assault but told AFP there were "very well-established procedures" in Hong Kong to handle police complaints.
Referring to any possible criminal prosecutions arising from the alleged police beating, Yuen said: "I can guarantee that if there is any need to move in that direction, my department will handle the matter in an independent and impartial manner."
Several thousand people had gathered late Wednesday at the main protest site in Admiralty to hear speeches by protest leaders, who urged demonstrators to stay peaceful in the face of violence.
"The major thing is people have realised how police become corrupt under a government that doesn't represent the people of Hong Kong," said Kay Wong, 25, a university research assistant.
"I was shocked at the police violence last night. Who wouldn't be?"
Tensions have risen in recent days as police began tearing down some barricades around protest sites. Officers have used fists, batons and pepper spray to beat back crowds in an operation they defended as a necessary response to ensure public order.
But footage from television network TVB later emerged of a group of plainclothes officers assaulting a handcuffed and unarmed protester, sparking outrage and calls for prosecution from activists and lawmakers.
It shows officers hauling the man to a dark corner of a public park, and placing him on the ground.
One officer stands over the man and punches him, as three others are seen repeatedly kicking him in an assault TVB said lasted four minutes.
Police later said seven officers had been identified in relation to the video.
The incident become another public relations disaster for the police, who were severely criticised for firing tear gas on umbrella-wielding protesters on September 28 in a move that attracted worldwide attention.
Demonstrators have also accused officers of failing to come to their aid during several attacks by violent pro-government thugs.
Prominent student leader Joshua Wong said trust between police and activists had hit an all-time low, while Amnesty International also condemned the "vicious" attack.
"It is stomach-churning to think there are Hong Kong police officers that feel they are above the law," Mabel Au, director of Amnesty Hong Kong said in a statement.
Hong Kong's security chief Lai Tung-kwok sought to ease tensions over the video, expressing "concern" and promising a "just and fair investigation", without specifying how many officers were being probed.
Following Wednesday's clashes, a Beijing official said China sees no need "so far" for its army to be deployed to contain the protests.
Rumours have frequently swept protest camps that the People's Liberation Army, which maintains a garrison in the city, will be deployed if Beijing feels Hong Kong police cannot handle the demonstrations.
"We hope that such a scenario will not unfold. The situation is gradually returning to normal," the official said on condition of anonymity.
Hong Kong's richest man, Li Ka-shing, urged protesters to leave the streets, saying they had got their message across.
"It would be Hong Kong's biggest sorrow if the rule of law is undermined," Li said in a statement.
Protests were largely peaceful until the clashes early Wednesday. But ugly scuffles have broken out between demonstrators and government loyalists, sparking accusations that the authorities are using hired gangsters.
Patience with protesters is running short in some quarters, with shop owners and taxi drivers losing business and commuters voicing irritation at disruptions and delays.
However citizens waited for hours Wednesday evening to file complaints about the videotaped beating.
"The police have completely lost the respect of the people of Hong Kong. I'm speechless," said one, Amy Chan.