Hong Kong police used tear gas, fire hoses and pepper spray to hold back hundreds of anti-WTO protesters, in the worst violence seen in the city for decades.

Demonstrators determined to disrupt the six-day World Trade Organisation meeting, due to end on Sunday, used metal railings as battering rams to try to smash through police lines near the venue where trade ministers were meeting.

<##IMAGE##>Some broke through and attacked officers with bamboo sticks and bars. In chaotic scenes, police grappled with protesters and dragged some away.

Police used dozens of tear gas canisters to force back the demonstrators Saturday evening, an AFP correspondent at the scene reported.

"The protesters have been pushed back with tear smoke by the Hong Kong police. You"re all perfectly okay," police officer Peter Hunt told delegates inside the WTO venue, a harbourfront convention centre which police had locked down.

A Hong Kong government spokesman said in a statement that 70 people had been sent to hospital for treatment following the protests, including 10 police officers. Three of the injured were in hospital.

Police chief Lee Ming-kwai told reporters 900 people had been temporarily detained, but there were no immediate figures for any arrests.

"At this moment in time, we have rounded up about 900 in the Wan Chai area," Lee said, referring to the waterfront district where the WTO venue is located.

In the early hours of Sunday, police rounded up a group of 300 hardline protesters -- mainly militant South Korean farmers -- who had been penned into a Wan Chai street for more than five hours, bussing them to a detention centre.

Lee said he did not expect similar violent protests on Sunday, the last day of the six-day WTO conference, which aims to draft a multilateral accord to boost trade in farm produce, industrial goods and services.

Lee said authorities were still considering whether to ban a protest planned for Sunday in light of the violence.

The police chief said trouble began when about 1,000 protesters suddenly charged a cordon keeping them away from the convention centre.

"A major confrontation ensued," Lee added, with protesters attacking police with iron poles and other hard objects and pushing down barriers. They also tried in vain to overturn a police van.

Demonstrations earlier in the week by South Korean farmers and other anti-globalization activists had been mild compared to mayhem at WTO meetings in Seattle in 1999 and Cancun in 2003.

But the South Koreans had vowed to make Saturday the day they would "escalate" their action ahead of the end of the six-day meeting.

Demonstrators suddenly split into at least two groups and tried to break through police lines, temporarily succeeding in some places.

Militant French farmer Jose Bove, best known for demolishing a half-built McDonald"s in the southern town of Millau in 1999, was among the protesters.

"The WTO fortress is surrounded by farmers," he said.

"The WTO is already dead. The people"s war against the WTO is already won."

Some Koreans dismantled barricades and armed themselves with the bars. Others pulled away police shields or used traffic cones and road signs as weapons. The crowds chanted "No to WTO!" as a helicopter passed over.

Each side later blamed the other for the violence.

"We tried to get our voices heard in a peaceful manner and hope the WTO will hear our demands. However police blocked our way: they shot tear gas at us," said South Korean protest leader Park Min-Ung.

"Police, please guarantee our safety, if you try to force us to disperse, we will react more strongly," said Park, general secretary of the Korean Peasants League, as some 20 protesters threw themselves against police lines.

Lee said police used a "minimum level" of force.

And Secretary of Security Ambrose Lee said demonstrators "have shown their true colours by resorting to violence, breaking our law and order and disobeying the instructions of our police officers."

Earlier Saturday, he pledged: "Police will take robust action to dispel these kinds of illegal and violent acts."

The violence was far less serious than in Seattle or Cancun but still highly unusual in this law-abiding southern Chinese city, where marches by hundreds of thousands of pro-democracy protesters in recent years have passed by without a single incident.

Police blocked off several roads including a six-lane highway and closed a subway station. Dozens of business premises were boarded up earlier in the week in expectation of trouble. Bars in the Wan Chai red light strip were among those pulling down the shutters Saturday night.

Hundreds watched the events from footbridges and other vantage points, taking pictures with mobile phones, before police cleared the area.

Police mounted one of their biggest-ever operations for the conference, putting 9,000 officers on duty.