Protesters in Geneva threw stones and firecrackers at the police, who responded with tear gas and water cannons during a demonstration Sunday against the G7 summit in nearby Evian.
Thousands had turned out in the Swiss city, to protest against the gathering of top world leaders, which starts across Lake Geneva in France on Monday.
As the clashes raged Sunday evening between some groups of protesters and police in several parts of Geneva, French President Emmanuel Macron, this year's summit host, arrived in Evian.
He will welcome the leaders of the other Group of Seven countries -- Britain, Canada, Germany, Italy, Japan and the United States -- to the lakeside spa town on Monday, along with invited leaders from several other countries, including Brazil and India.
The three-day summit will be one of the first major international gatherings since the United States and Israel launched a war against Iran in late February, upending the Middle East and widening transatlantic tensions.
Most protesters peaceful
The group will have a packed agenda of potentially explosive issues, including efforts to end the war in Iran, with US President Donald Trump's claims of an imminent deal shrouded in uncertainty.
Ukrainian President Volodymyr Zelensky is also due to attend, putting the war sparked more than four years ago by Moscow's full-scale invasion in keen focus.
Most of the leaders, including Trump, will be arriving at Geneva Airport, before making the journey to Evian.
Geneva -- about 40 kilometers southwest of Evian -- had been on edge or weeks.
The city's authorities were anxious to prevent a repeat of the mayhem of 2003, when anti-G8 rioters caused millions of dollars worth of damage in the Swiss city.
This time, the Geneva authorities had permitted a march around a lengthy loop on the north side of the city -- well away from the city centre and its luxury boutiques.
By Saturday, small shops, supermarkets and university buildings -- some of them far from the protest route -- had boarded up their facades.
Despite the precautions however, some protesters caused extensive damage on Sunday.
Most of the 20,000 or so demonstrators who according to police took part in the protests, were peaceful.
Waving banners with messages like "No to the G7 and all imperialist alliances!" and "Abort the G7", the protesters gathered in a park on the shores of Lake Geneva. They then made their way through a barricaded city that seemed to be bracing for an invasion, as helicopters hovered above.
Under a burning sun, they set off chanting slogans with a range of messages, supporting Palestinians, climate action, feminism and anti-capitalist activism.
"I'm here because I'm not happy that this group of heads of state is meeting here to make decisions that affect all of us," Michel, a 69-year-old Swiss retiree waving a Palestinian flag, told AFP.
'Eat the Rich'
But shortly after the march began, several groups of black-clad protesters broke barriers protecting affluent apartment buildings along the way and set cars alight.
AFP journalists saw a Tesla car ablaze, tagged with the words: "Eat the Rich", and a number of buildings around the United Nations' European headquarters were damaged.
Clashes with police followed, as protesters chanting "Down with the police state" threw bottles, pieces of cement ripped up from the sidewalks, and firecrackers, and were met with clouds of tear gas and water cannons.
Several hours in and with clashes still ongoing, police said that around 600 so-called "Black Bloc" radical protesters had taken part.
Due to conditions imposed by the French authorities, the No-G7 coalition abandoned plans for a counter-summit and demonstration Sunday in the French border town of Annemasse.
Switzerland mobilised up to 4,000 troops to support police forces, while France has announced the deployment of nearly 16,000 police, gendarmes, troops, firefighters and border guards around Evian.
(With newswires)
