Riot police moving against activists sparked outrage after officers were seen kicking a handcuffed protester and dragging dozens of others away Wednesday in the worst violence against the pro-democracy demonstrations in Hong Kong since they began more than two weeks ago.

Clashes that erupted before dawn Wednesday continued early Thursday, as police used pepper spray to push back crowds of protesters trying to occupy a road outside the government's headquarters.

Tensions were high but the scenes were not as chaotic as on Wednesday, when protesters were knocked to the ground by hundreds of police, some with batons, pepper spray and shields.

The clashes have worsened an already bitter standoff between authorities and activists who have taken over key roads and streets in the city to press for democratic reforms.

"Hong Kong police have gone insane today, carrying out their own punishment in private," said pro-democracy lawmaker Lee Cheuk-yan. "Hong Kong's values and its rule of law really have been completely destroyed by police chiefs."

Police arrest 45

Public anger over the aggressive tactics exploded after local TV showed officers taking a protester around a dark corner and kicking him repeatedly on the ground. It's unclear what provoked the attack. Local Now TV showed him splashing water on officers beforehand.

Protester Ken Tsang said he was kicked while he was "detained and defenceless." He added that he was assaulted again in the police station afterwards.

HONGKONG-CHINA/

A police officer yells at protesters to move away from the road as they try to block an area near the government headquarters building in Hong Kong on Wednesday. (Carlos Barria/Reuters)

Tsang, a member of a pro-democracy political party, lifted his shirt to show reporters injuries to his torso and said he is considering legal action against police.

Police spokesman Steve Hui said seven officers who were involved have been temporarily reassigned, and that authorities will carry out an impartial investigation. Police arrested 45 demonstrators in the clashes, and said five officers were injured.

China's central government issued its harshest condemnations yet of the protests, calling them illegal, bad for business and against Hong Kong's best interests. Beijing has become increasingly impatient with the demonstrations, the biggest challenge to its authority since China took control of the former British colony in 1997.

A front-page editorial Wednesday in the People's Daily, the ruling Communist Party's mouthpiece, condemned the protests and said "they are doomed to fail."

'Stability is bliss, and turmoil brings havoc.' - People's Daily editorial

"Facts and history tell us that radical and illegal acts that got their way only result in more severe illegal activities, exacerbating disorder and turmoil," the commentary said. "Stability is bliss, and turmoil brings havoc."

The BBC reported that access to its English-language website has been blocked "across China." The network's global news director said it appeared to be "deliberate censorship," but the reason for the blackout wasn't clear.

Beijing has shown no signs it's planning to become directly involved in suppressing the mostly peaceful demonstrations, which began Sept. 26 and have posed an unprecedented challenge to the government.

The protests have marshalled opposition to plans for a pro-Beijing committee to screen candidates in Hong Kong's first election to choose the city's chief executive in 2017. Activists also want Leung Chun-ying, the current leader who is deeply unpopular, to resign.

'Out of control'

Leung, who described the protests as being "out of control," told reporters that officials are willing to talk to protesters, but reiterated that Beijing will not drop the election restrictions. He canceled a leader's questions session at the Legislative Council on Thursday, citing security risks.

Hong Kong Democracy Protest

A protester leans over barricades after scuffling with police as they were trying to remove barricades that protesters have set up to block off main roads in Central district in Hong Kong on Wednesday. (Vincent Yu/The Associated Press)

In Washington, State Department spokeswoman Jen Psaki said the U.S. was deeply concerned by the reports of the police actions and urged a "swift, transparent and complete investigation." She said respect for rule of law and fundamental freedoms remained crucial to Hong Kong's reputation as a center of global commerce, and reiterated a U.S. call for Hong Kong authorities to show restraint.

The police operation early Wednesday came hours after a large group of protesters blockaded the underpass, expanding their protest zone in apparent retaliation after police closed in on the occupied areas and cleared activists out of a key thoroughfare.

Police said the protesters were gathering illegally and disrupting public order, and thus had to be dispersed. They added that the activists were using umbrellas to attack officers. Umbrellas have been a symbol of the demonstrations after protesters used them to fend off tear gas and pepper spray last month.

"Some of us were sleeping in the park when more than a hundred of them ran toward us with torches as if they're trying to blind us temporarily. We were not prepared for how aggressive they were," said protester Simon Lam, 22.

With files from CBC News