The United States has called for a "swift, transparent and complete" investigation into the beating of a handcuffed Hong Kong democracy protester by plain-clothes police, as fresh street clashes broke out early today.
Television footage of officers assaulting the unarmed protester in a dark corner of a public park has sparked outrage and calls for prosecution from activists and lawmakers in the city.
Tensions soared after the video went viral yesterday, with protesters saying they had lost all faith in the police despite the accused officers being "reassigned" from their posts by city authorities.
The United States said it was "deeply concerned" by the police brutality reports.
"We encourage Hong Kong authorities to carry out a swift, transparent, and complete investigation into the incident," US State Department spokeswoman Jen Psaki said.
"We renew our call for the Hong Kong government to show restraint, and for protesters to continue to express their views peacefully."
Hong Kong has been rocked by mass rallies for much of the last two weeks, calling for full democracy and causing significant disruption to a city usually known for its stability.
Protesters are angry at the central government's insistence that it vet candidates standing for election as the city's next leader in 2017, a proposal they have dubbed "fake democracy".
After weeks of largely giving control to protesters at three main sites, police have begun investigating demonstrator defences in the last few days, tearing down some barricades and causing running battles.
But Hong Kong authorities face a bigger backlash after video was aired showing officers hauling a handcuffed protester to the quiet corner of a public park, placing him on the ground and beating him with kicks and punches.
"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.
The incident has 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.
Britain weighs in
British Prime Minister David Cameron meanwhile said Britain would stand up for Hong Kong's rights and freedoms, "including those of person, of speech, of the press, of assembly", while his spokesman later urged police and protesters to calm down.
Renewed clashes between police and protesters broke out again in the early hours of this morning over a contested road near Chief Executive Leung Chun-Ying’s offices.
Officers used pepper-spray against defiant demonstrators shouting chants accusing them of links with triad gangs - but the flurry of violence was brief compared to the night before.
Several thousand gathered late on 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?"
Police said seven officers had been identified in relation to the video and that they would be given other jobs. Police would investigate the incident.
Hong Kong's justice chief insisted on Wednesday that any prosecution of plainclothes officers who were filmed beating a handcuffed protester would be handled fairly, while security chief Lai Tung-kwok also promised a "just and fair investigation", without saying how many officers were being probed.
No army yet
Following Wednesday’s clashes, a Beijing official said China saw no need "so far" for its army to be used to contain the protests.
Rumours have frequently swept protest camps that the People’s Liberation Army, which has a garrison in the city, will be used if Beijing feels Hong Kong police cannot handle the demonstrations.
Go home, says Li Ka-shing
Hong Kong’s richest man, Li Ka-shing, urged protesters to leave the streets, saying they had got their message across.
Protests were largely peaceful until the clashes early on Wednesday. Although ugly scuffles have broken out between demonstrators and government loyalists, causing accusations that the authorities are using hired gangsters.
Patience with protesters is also running short in some quarters, with shop owners and taxi drivers losing business and commuters voicing irritation at disruptions and delays.