HONG KONG -- Hundreds of Hong Kong police officers drove protesters from a tunnel in the dead of night in 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 protesters, tore down barricades and removed concrete slabs the protesters used as road blocks around the underpass.

The clampdown comes amid increasing impatience in Beijing over the political crisis in the semi-autonomous Chinese territory.

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, referring to the activists.

"Stability is bliss, and turmoil brings havoc," it said.

The operation came hours after a large group of protesters blockaded the tunnel, 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.

Officers took away many protesters, their hands tied with plastic cuffs, and pushed others out to a nearby park.

Police said they had to disperse the protesters because they were disrupting public order and gathering illegally. They arrested 45 activists 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 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 who in 2012 interrupted Leung's inauguration by heckling then-Chinese President Hu Jintao.

The student-led protesters are now into their third week of occupying key parts of the city to pressure the Asian financial centre's government over curbs recommended by Beijing on democratic reforms.

They oppose plans for a pro-Beijing committee to screen candidates to run in Hong Kong's first direct elections to choose a leader, called a chief executive, in 2017. They also want the current chief executive, 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.

Leung has said there is "almost zero chance" that China's government will change its rules for the election.

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.

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.

Police have chipped away at the protest zones in three areas across the city by removing barricades from the edges of the protest zones. On Tuesday, they used chain saws and sledgehammers to tear down barricades at the edge of the protest zone.

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 a statement from the central government's liaison office in Hong Kong, director Zhang Xiaoming told city legislators at a banquet Tuesday that the protest movement "is a serious social and political incident that has violated the 'one country' principal, challenged the central authority," and is "an illegal activity that openly violates Hong Kong's current law."

"It has not only brought to Hong Kong economic losses in tens of millions of yuan, affected the livelihood of vast numbers of citizens, but also hurt the basis of Hong Kong's rule of law, democratic development, social harmony, international image and its relations with the mainland," Zhang said, calling for the movement to be ended as soon as possible.

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