Hundreds of police have used chainsaws and bolt-cutters to dismantle barricades put up by pro-democracy activists near the government offices in Hong Kong.
They also re-opened a main thoroughfare in Causeway Bay, a shopping district.
Demonstrators have occupied parts of Hong Kong for more than two weeks.
The activists, a mix of students and a pro-democracy group called Occupy Central, are demanding a fully democratic election in 2017.
China, which has control over Hong Kong, says residents can vote – but it will vet which candidates are eligible to stand.
On Monday, scuffles broke out between those opposed to the Occupy movement and demonstrators after police removed some barricades in Central district.
The protesters than reinforced their barricades overnight, building bamboo barriers, and laid down cement foundations.
On Tuesday, police arrived with bolt cutters, chainsaws and sledgehammers. Local media said they were using the chainsaw to cut through the bamboo barriers.
“Police have decided to take the next step in action to take away unlawful obstacles on the westbound lane and tram lines of Queensway,” a police spokesman told AFP news agency ahead of the operation.
Some protesters were visibly distressed. “We are only residents and students,” one protestor shouted according to AFP. “We will leave as we are unable to fight you but we will not give up.”
At the start of the protests last month thousands of people were on the streets, with hundreds sleeping there overnight. However, numbers have dwindled in recent days.
Over the weekend, Hong Kong’s embattled leader CY Leung said the protestors had zero chance of changing Beijing’s mind on constitutional reform.
He added that the protest movement had spun out of control.