Sixty people were arrested after hundreds of protestors converged on the centre of Geneva to protest against the World Economic Forum in Davos in defiance of a ban imposed by local authorities, a police spokesman said.
Organisers had appealed for calm, while attacking the ban on the march.
But bottles and firecrackers were thrown at the riot police who charged the demonstrators, using teargas grenades.
"Around 60 people were arrested, of whom 20 have already been released," police spokesman Jean-Philippe Brandt said two hours after the start of the protest.
He said no injuries had been reported on either side, adding that most demonstrators had been dispersed and only a hard core of some 100 radicals were being contained by police.
After tentatively allowing the rally to go ahead, the regional government said earlier this month the organisers of the demonstration had been unable to provide sufficient security guarantees to stage the event in the western Swiss city.
Police equipped with a water cannon had blocked the planned route of the march, while participants were systematically checked and their bags searched.
In Davos itself, a group of several dozen protestors marched through the snow-covered Alpine village, holding a giant banner that read "You Are The Crisis".
Another small group chanting "No To the WEF" threw fake blood on security barriers and ripped down sheeting on the perimeter.
Anti-globalisation groups frequently protest against the annual meeting of the select group of the world's business and political elite in the eastern mountain resort of Davos, although demonstrations have subsided in recent years.
Laurent Moutinot, the Geneva canton's minister in charge of home affairs and policing, said last week, "We're not facing a popular movement, but a group of people who deliberately aim to come here for a bust-up."
Banners being carried Saturday called for freedom of expression and attacked the "capitalist swindle", claiming that "the blackmailers of the WEF are mortgaging our future."
Some demonstrators disguised as clowns attempted to provoke the police by ridiculing them.
Later Saturday a "large group" returning to the capital Bern from the Geneva protest tried to hold a demonstration but were dispersed by security forces who used teargas and rubber bullets, Bern police spokesman Franz Maerki said.
Organizers protested strongly over the banning of the Geneva demonstration, with Eric Decarro of the Solidarites union declaring: "The government of Geneva canton banned a demonstration for the first time in 35 years."
Earlier this month a Swiss group of "anarchist and communist political forces" put out posters depicting fiery images of masked protestors, calling for people to join the "revolutionary block" or to "smash WEF."
That stirred up memories in Geneva of protests against a meeting of G8 industrialised countries in nearby France in 2003, which turned into running overnight battles between rioters and police and left shops ransacked.
Although the Davos meeting takes place on the other side of the country, the WEF's administrative headquarters are just outside Geneva and the prosperous city's private banks and commodity traders are taken as something of a symbol for capitalism.
Davos, perched high in the Alps, is also cordoned off by a massive security operation during the event, but a small authorised demonstration of a few dozen people took place there Saturday.
Police kept a low profile, and only some symbolic snowballs and a few shoes were thrown by the protestors.
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