Updated

Hundreds of Hong Kong police officers drove protesters from an underpass in the dead of night Wednesday, the worst violence since the street demonstrations for greater democracy began more than two weeks ago.

Officers, many with riot shields and wielding pepper spray, dragged away dozens of activists, tore down barricades and removed concrete slabs the protesters used as road blocks around the underpass.

Beijing issued its harshest condemnations yet of the protests, calling them illegal, bad for business and against Hong Kong's best interests. The central government has become increasingly impatient with the demonstrations, the biggest challenge to Beijing's 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."

"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," it said.

However, there were no signs that the central government was planning to become directly involved in suppressing the demonstrations, which are pushing for greater say in choosing the territory's next leader in 2017 elections.

The police operation came hours after a large group of protesters blockaded the underpass late Tuesday, expanding their protest zone after being cleared out of some other streets. The protesters outnumbered the police officers, who later returned with reinforcements to clear the area.

The underpass borders the city government headquarters and is a short walk away from the main protest zone straddling a highway on the opposite side of the complex. Demonstrators appeared to storm the short tunnel in reaction to police attempts over the past two days to chip away at barricades on the edges of the sprawling protest zone.

Police said they had to disperse the protesters because they were disrupting public order and gathering illegally. They arrested 45 demonstrators during the clashes, which police said injured four officers.

"I have to stress here that even though protesters raised their hands in their air it does not mean it was a peaceful protest," said the spokesman, Tsui Wai-Hung. He said some protesters kicked the officers and attacked them with umbrellas.

None of those arrested were hurt, he said.

But local television channel TVB showed footage of around six plainclothes police officers taking a man around the side of a building, placing him on the ground and kicking him. Tsui did not provide details of the incident when questioned by reporters.

Local legislators and activists identified the protester as Ken Tsang, a member of a local pro-democracy political party.

Secretary for Security Lai Tung-kwok later told reporters that the officers who were involved have been reassigned and the police department is carrying out an investigation.

The student-led protesters are now into their third week of occupying key parts of the city. They oppose plans for a pro-Beijing committee to screen candidates to run in Hong Kong's first direct elections to choose the city's chief executive in 2017. They also want the current leader, Leung Chun-ying, to resign.

When negotiating the 1997 handover of Hong Kong from Britain, China's ruling Communist leaders agreed to a "one country, two systems" that would preserve Western-style civil liberties and broad autonomy in the territory, while promising eventual democracy. Protesters see Beijing as reneging on that promise.

After initial attempts to disperse the protesters with tear gas and pepper spray two weeks ago, police have adopted a different strategy of chipping away at the protest zones in three areas by removing barricades from the edges of the areas they are occupying at night or in the early morning.

On Tuesday, they used chain saws and sledgehammers to tear down barricades at the edge of one of the protest zones.

Positions on both sides have been hardening since the government called off negotiations last week, citing the unlikelihood of a constructive outcome given their sharp differences. Leung has said there is "almost zero chance" that China's government will change its rules for the election.

The demonstrations have posed an unprecedented challenge to the government. Organizers say as many as 200,000 people thronged the streets for peaceful sit-ins after police used tear gas on Sept. 28 to disperse the unarmed protesters. The numbers have since dwindled.

Beijing is eager to end the protests to avoid emboldening activists and others on the mainland seen as a threat to the Communist Party's monopoly on power.

In language freighted with political symbolism, Zhang Xiaoming, director of the central government's liaison office in Hong Kong, was quoted as telling Hong Kong legislators at a banquet Tuesday that the protest movement "is a serious social and political incident."

Zhang said the movement challenged Beijing's authority and had caused the city to suffer huge economic losses. They had "hurt the basis of Hong Kong's rule of law, democratic development, social harmony, international image and its relations with the mainland," he said.

Zhang called for an end to the protests as soon as possible to avoid further losses to Hong Kong's citizenry as a whole.

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Associated Press writer Didi Tang in Beijing contributed to this report.

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