HONG KONG >> Pro-democracy demonstrators battled the police for control of important downtown arteries here into the early hours on Wednesday, with the police pushing protesters out of a park using pepper spray and wrestling some of those who resisted to the ground.

The violent confrontation came hours after tit-for-tat actions escalated a tense standoff in this Asian financial center and as the authorities showed growing impatience with the protests that have choked traffic in the city for more than two weeks.

On Tuesday morning, the police drove protesters off a major road, using chain saws to dismantle the barricades they had built there. Hours later, the protesters braved pepper spray to seize a street tunnel near the offices of Hong Kong’s leader.

The latest confrontation, which started about 3 a.m. Wednesday, was near the tunnel as hundreds of police wielding batons and shields moved in on a crowd of hundreds of demonstrators in the park nearby.

The police action came as pressure on the Hong Kong authorities grew after the Chinese government made its highest-level denunciation yet of the protesters, accusing them of pursuing a conspiracy to challenge Beijing’s power over the city.

Zhang Xiaoming, the head of the central Chinese government’s liaison office in Hong Kong, said the movement had "provoked" the central Chinese government and engaged in "radical forms of street confrontation," the China News Service, an official news agency, reported.

"The best way to avoiding having all of Hong Kong’s residents pay a steeper price," he was reported as saying, was to end the movement "as soon as possible."

On Tuesday night, hundreds of protesters occupied the short traffic tunnel near the offices of Hong Kong’s chief executive, Leung Chun-ying, after facing off against rows of police officers in riot-control gear. Witnesses said the officers used pepper spray as they tried to hold back the demonstrators, some of whom shielded themselves with umbrellas, the symbol of their movement. After a brief, chaotic standoff, the police retreated and the crowd cheered.

Some said the move to the tunnel was prompted by the arrest of a protester, but most described it as retaliation for the police operation Tuesday morning that cleared Queensway, a vital eight-lane road near the main protest camp in the Admiralty neighborhood on the south side of Victoria Harbor.

"This is a way of getting back," said Andy Siu Au-yeung, a designer who helped build new roadblocks. "I don’t know who had the idea. It was just spontaneous."

In the early hours of Wednesday, the tunnel remained a hive of defiant activity. Students and white-collar workers milled around inside, taking triumphant photographs and using their now well-practiced methods to lash together metal and plastic police barriers into elaborate roadblocks. They then piled on trash cans, road signs and other heavy objects to bolster their defenses.

The police, on a loudspeaker, warned the protesters against using police barriers in the fortifications. But the crowd bristled, and many shouted dismissive jeers at the officers.

Not all participants were enthusiastic, though, and some feared a more serious confrontation. "I’m not sure we can maintain this," said Fan Yiu-kam, a structural engineer in his 20s watching the new barriers go up. "Tomorrow morning will be critical, when many people go to work and then we’ll have fewer people here," he said. "The strongest barricade is a lot of people, but we don’t always have that."

The protesters took control of the tunnel more than 12 hours after hundreds of police officers swooped onto Queensway and swiftly tore down barriers that protesters had erected overnight to defend their main camp.

"If protesters try to rebuild the barricades, it absolutely will not be tolerated," Hui Chun-tak, the chief police spokesman, said in the afternoon, before the takeover of the tunnel. (The tunnel is on a road that runs roughly parallel to Queensway but is smaller.)

Hui also indicated the authorities’ efforts to shrink areas under the protesters’ control would continue. He said the police planned to remove obstacles in the bustling Mong Kok neighborhood on the north side of Victoria Harbor, which has been the site of a raucous, occasionally violent street occupation.

"Mong Kok is a high-risk area — our officers are now ready to take action," he said. Hui said the goal of the action, as elsewhere, would be to remove obstacles impeding traffic and not to clear the demonstrators themselves from the streets, unless the demonstrators resisted. He gave no specific time for action in Mong Kok, despite repeated questions.

Nathan Road in Mong Kok, a usually frenetic shopping strip where demonstrators have blocked traffic, was busy with protest meetings Tuesday night. Hundreds of police officers stood watch around the site or in nearby streets, but there were no signs of any impending operation to remove the barriers.

The police had earlier removed some of the metal railings taken by protesters for the barriers, but they were quickly replaced with wooden pallets.

Several people in the crowd said the protesters at Mong Kok, where there is a higher proportion of workers and hardened political activists than Admiralty, were likely to fiercely resist any police incursions. "No road opening without concessions from the government," said one poster.

"I agree with that," said Calvin Chan, a 31-year-old electronics merchandiser who was reading the poster. "If we move away now, what have we done?" he said. "If the police try to clear here, there could be blood. Some of the people are quite stubborn."

Vicky Koo, a social worker in the Mong Kok area, said, "Here there is no union or organization, and less students. If the police move in, it will be harder to control the conflict."

Although many protesters at the Admiralty camp proclaimed they would defy further incursions, their resistance could prove brittle if the police again take them by surprise and overwhelming force.

"We need more people to come out and use their power, but it’s hard because everyone needs to work," said Kevin Sze, a 26-year-old social worker, as he sat on a camping chair near the barricades remaining around Admiralty. He was between jobs, and so had been able to stay at the protest site during the day, he said, adding, "No one wants to be arrested."

In the main protest camp there — a settlement of tents, supply stations and protest art next to the government offices — some protesters voiced worries that the police would continue encroaching on the encampment. But many said that they would stay and resist if the police tried to move in closer.

Alex Chow, the secretary-general of the Hong Kong Federation of Students, one of the main organizations supporting the protests, said in an interview that he was "somewhat relieved" that the protesters no longer had to defend Queensway. The retreat could help consolidate protesters’ strength at other sites and ease residents’ complaints about the inconveniences caused by the roadblocks, he said.

"It’s not a wholly ideal strategy to occupy Queensway in the first place," he said. "The inconvenience cost us sympathizers, and the fact is you don’t have enough people to defend it."

The protests have polarized Hong Kong society between supporters of demonstrators’ demands for electoral democracy and opponents who see the protests as disruptions to the city’s usual orderliness. Some Hong Kong politicians, echoing accusations in the Chinese Communist Party press, also suggest that the demonstrations are Western-inspired challenges to the Chinese government’s hold over the former British colony.

Beijing regained sovereignty over Hong Kong in 1997, and it has promised residents that from 2017 they would have the right to vote for the city’s leader, or chief executive.

But democrats argue that the electoral rules laid down by China’s legislature in late August would turn such elections into an empty ritual, because they require that candidates first win approval from at least half the members of a nomination committee dominated by groups and politicians loyal to Beijing.

Regina Ip, a Hong Kong lawmaker who supports Chinese government policies toward the city, told reporters on Tuesday that the protests were tarnishing Hong Kong’s image of stability. "We are beginning to see a breakdown of law and order," she said. "The lawlessness that is surfacing is disturbing. This is not what Hong Kong is famous for."

But Audrey Yu, the chairwoman of the pro-democratic Civic Party who supports the sit-ins, said in an interview that the protest movement needed to maintain public support and prepare for a long struggle similar to the civil rights movement in the United States.

"I’ve been going to these mobile civic classes, and I’ve been telling them about Rosa Parks," she said. "I always ask them, ‘How long do you think the Montgomery bus boycott lasted?"’

"A lot of people said, ‘A month?’ ‘Three months?’?" Yu added. "And I said no, and they finally said, ‘A year!’ So I think you have to prepare to have staying power."