Seventy-four people were injured in the fighting on Saturday, including 12 police officers, the government said. Most of the injuries were minor and most of the injured were South Korean farmers and workers protesting against free-trade agreements.
The clashes were the heaviest since the six-day World Trade Organisation meeting began on Tuesday.
About 900 protesters were rounded up on one road in the area, Dick Lee, the police commissioner, told a late-night news conference. Asked if they would be arrested, he said: "They will be handled according to the law.
"At the moment, the majority of areas in Wanchai are under control.
"Police will be taking all necessary action to restore order. We are fully confident the venue [trade meeting] can proceed as normal."
Protests planned for Sunday
About 1000 protesters were involved in street battles, confronting twice as many police, Lee said.
Seventy-four protesters were
injured on Saturday
Police said they had not yet decided whether another large demonstration scheduled for Sunday would be allowed to proceed.
At one point on Saturday, protesters seized metal barricades and used them as battering rams against the police, but police lines held and reinforcements pushed the protesters back.
Police fired volleys of teargas near the building, Reuters correspondents said, and television showed officers bringing up what appeared to be armoured vehicles.
European and Japanese delegates were taken to the centre at the harbour by boat for late-night meetings, as fighting raged.
Protesters wielding bamboo sticks and iron poles began storming heavily fortified police lines in the late afternoon, breaking through ranks of police who used pepper spray, batons and blasts of water from fire hoses to try to beat them back.
Early on Sunday, seven hours after the fighting began, police moved in and started rounding up the last several hundred protesters who had been staging a sit-in.
"We love Hong Kong," some of the demonstrators chanted as police encircled the group. "Down, down WTO."
Protesters stormed heavily
fortified police lines
An estimated 10,000 anti-globalisation protesters converged on Hong Kong for the trade meeting, including about 2000 South Korean farmers, workers and unionists, who have a reputation as the most militant anti-globalisation group in Asia.
The violence had no impact on the negotiations inside, where ministers from 150 states were struggling to reach minimal accords.
Diplomats said a failure to resolve the sticking points before talks end on Sunday would reduce the chances of a deal next year, freeing up global business in farm and industrial goods and services.
Mukhisa Kituyi, Kenya's trade minister, said: "Either everything will unravel and we will have another Cancun situation - I hope it won't happen - or we'll have lowered ambitions in the meeting in Hong Kong."
Kituyi, who has mediated on agricultural issues at the talks in Hong Kong since they got under way on Monday, was referring to the acrimonious collapse of negotiations on the so-called Doha trade round at a WTO meeting in Cancun, Mexico, two years ago.
A draft of the final declaration, released after negotiators worked through the night, showed that there was still no agreement on setting a date for ending farm export subsidies.