DAVOS, Switzerland About 100 Occupy protesters gathered in front of the town hall in this Eastern Switzerland resort where the World Economic Forum is being held.
Some held placards with slogans such as "If voting would change anything, it would be illegal" and "Don't let them decide for you, Occupy WEF."
A small group of protesters are camped in igloos in Davos to call for more help for the needy.
Later, a small group split from the rally and marched toward the forum, prompting about a dozen police officers to hastily erect a mobile barrier as Saturday shoppers looked on with bemusement.
The demonstrators chanted anti-capitalist slogans and engaged in a brief violent standoff with police that resulted in a car's rear window being smashed. Officers used pepper spray against the protesters and detained seven people, Hobi said. Nobody was injured.
On Friday a member of the Occupy camp was invited to speak at a special event outside the forum on Friday night to discuss the future of capitalism; British opposition leader Ed Miliband was also speaking.
Soon after the panel discussion began, some activists in the audience jumped up and started chanting slogans, and the protester panelist walked off the stage.
Other members of the audience told the activists to "shut up" and arguments disrupted the panel for about 20 minutes. The discussion then resumed, without the Occupy panelist.
After the debate, the Occupy panelist, Maria (who declined to give her last name), said she wasn't surprised at the tumult: "There's the idea of experts sitting up somewhere and telling us what to do, and then we are here, and we refuse to discuss in that way. We want to empower the people to take action and to think of themselves." she said.
The moderator, British financial journalist Larry Elliott, admitted that it had been a difficult evening.
"It's not very often that you find the meeting hijacked, or attempted to be hijacked, right from the start," he acknowledged.
In a separate rally on Saturday, three topless Ukrainian protesters were detained Saturday while trying to break into an invitation-only gathering of international CEOs and political leaders to call attention to the needs of the world's poor.
After a complicated journey to reach the heavily-guarded Swiss resort town of Davos, the Ukrainians arrived at the entrance to the complex where the World Economic Forum takes place every year.
With temperatures around freezing in the snow-filled town, they took off their tops and tried to climb a fence before being detained. "Crisis! Made in Davos," read one message painted across a protester's torso, while others held banners that said "Poor, because of you" and "Gangsters party in Davos."
Davos police spokesman Thomas Hobi said the three women were taken to a police station and told that they weren't allowed to demonstrate without a permit or naked. They were released later Saturday.
The activists are from the Ukrainian group Femen, which has staged small, half-naked protests to highlight a range of issues including oppression of political opposition.
"We came here to Switzerland to Davos to explain the position of all poor people of the world, to explain that we are poor because of these rich people who now sit in the building," said Inna Schewcenko.