Hundreds of demonstrators have clashed with riot police near the world trade talks in Hong Kong.
Nine hundred have been "rounded up", police say.
Some stormed police lines around the centre.
Officers used pepper spray and batons to push them back.
Correspondents say the unrest is the worst street violence in Hong Kong for 16 years.
The scuffles involve South Korean farmers, South East Asian groups and European activists.
The Koreans - who are among the most vocal of the protesters - had vowed to step up action on Saturday.
They object to the current world trading system.
The protests came on the penultimate day of the summit.
Some protesters have pledged to stay outside the conference centre all night.