Swedish police officers block neo-Nazi demonstrators from deviating from a court-ordered route keeping them away from a synagogue in central Gothenburg on Sept. 30. (Tt News Agency/Reuters)

At least 50 people were detained Saturday during a far-right demonstration in Gothenburg, Sweden’s second-largest city, that left one police officer and several others injured, according to police reports.

The Nordic Resistance Movement (NRM), a neo-Nazi group founded in Sweden but steadily growing in influence in Finland and Norway, had said on its websites that it expected 1,000 people to march Saturday.

Police placed the number closer to 600, making it the largest neo-Nazi rally in Sweden in recent years.

Black-clad demonstrators bearing shields and waving the group’s green-and-white flag marched in the city’s center. NMR is known for its openly anti-Semitic stance, and the group had originally sought to pass by a downtown synagogue to coincide with Yom Kippur, the Jewish holy day.

Local activists protested, and a Swedish court intervened to shorten the march route so it would not pass near the synagogue. According to police reports, clashes broke out between police and NRM supporters when marchers attempted to deviate from the court-ordered route.

The rally sparked anxiety about the rise of the far right in Sweden and elsewhere in Europe, and a large counterdemonstration drew about 10,000 people from across the country.

“I am very concerned there will be more rallies like this in the future,” said Maxim Thore, an 18-year-old photography student who was among the counterprotesters. “The Nazis said at the protest that they will have a protest like this every Saturday from now on. I know people will always stand against them, but I don’t think 10,000 protesters can gather every Saturday.”

The counterprotesters clashed with the neo-Nazi marchers, throwing fireworks at the rally and getting into altercations with NMR members who attempted to cross police lines.

Thirty-five people were arrested, including NMR leader Simon Lindberg, police spokeswoman Emelie Kullmyr said.

“Three have been arrested for violence against the police and two others for bearing arms,” Kullmyr said.

The night before the protest, 20 people, mostly Danes and Germans, were stopped as they arrived in Sweden to take part in the rally.

Membership in Nazi organizations is not illegal in Sweden. The NMR claims to follow the National Socialist doctrine of Adolf Hitler, and it opposes mass migration and what it calls “a global Zionist elite.”

A week before the rally, Swedish Prime Minister Stefan Lofven called for a halt to far-right activity in the country.

“When we now see an escalation of these extremist forces, and we are moving toward a normalization of racist parties, too, then we must do something,” Lofven said.