Hong Kong police fired volleys of tear gas today to repel hundreds of protesters trying to force their way into a building where world trade ministers were meeting.
"The protesters got very close to the building, they were standing just across the street," a witness said.
"They made several advances on police but pulled back a block or so after tear gas was used."
Seventy-four people were injured in the fighting, including 12 police officers, the government said. Most of the injured were South Korean farmers, who say free trade is ruining them.
Nine hundred protesters were detained, Police Commissioner Dick Lee 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," Mr Lee said.
"Police will be taking all necessary action to restore order. We are fully confident the venue (trade meeting) can proceed as normal."
Some 1,000 protesters were involved in the unrest, Mr Lee said. Police said they had not yet decided whether another large demonstration scheduled for tomorrow would be allowed to proceed.
It was the worst street violence in Hong Kong since angry protests following the Chinese army's bloody crackdown on pro-democracy protesters in Tiananmen Square in Beijing in 1989.
But the fighting was less intense than that which marred the last two big World Trade Organisation conferences in Cancun and Seattle.
A South Korean farmer stabbed himself to death in the Mexican town of Cancun during a WTO meeting in 2003. At one point today, 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 numerous volleys of tear gas in the area near the building,
Inside the convention centre, trade ministers continued their quest to find an elusive world trade deal, which critics say will hurt the world's poor.
Journalists, delegates and policemen crowded round TV monitors watching the brawls outside. European and Japanese delegates were taken to the harbourfront centre by boat for late-night meetings as fighting raged.
Protesters began storming heavily fortified police lines in late afternoon, breaking through ranks of police who used pepper spray, batons and fire hoses to try to beat them back.
Early on Sunday morning, some 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 in the area.
"We love Hong Kong," some of the demonstrators chanted as wary police encircled the group. "Down, down WTO."
Policewomen were the first to wade into the crowd, dragging some female protesters away one by one and packing them into police buses as remaining demonstrators started singing protest songs.
Others walked quietly to the buses escorted by police. It was not clear where the protesters were being taken.
Earlier, police had told them they were under arrest. Thousands of protesters from numerous anti-globalisation groups had taken to the streets in the early afternoon, handing pink and yellow roses to police officers manning barricades and releasing yellow balloons printed with
"No, no WTO". As numbers swelled, they began to push against police and probe their defences. An estimated 10,000 anti-globalisation protesters converged on Hong Kong for the trade meeting, including about 2,000 South Korean farmers, workers and unionists, who have a reputation as the most militant anti-globalisation group in Asia.