HELSINKI -- Three people have been arrested for allegedly throwing firebombs at a synagogue in the Swedish city of Goteborg, the second anti-Jewish attack in the Nordic nation in two days. Jewish groups condemned the attacks as "unconscionable" and demanded that authorities take action.

No one was injured in the attack late Saturday during a youth event at the synagogue and the adjacent Jewish centre in Sweden's second-largest city. Goteborg police spokesman Peter Nordengard said Sunday it is being investigated as an attempted arson.

The attack took place after some 200 people rallied late Friday in the southern city of Malmo, yelling anti-Jewish slogans and waving Palestinian flags to protest U.S. President Donald Trump's decision to recognize Jerusalem as Israel's capital.

Witness Allan Stutzinsky told the TT news agency he saw a dozen masked youths who threw what appeared to be firebombs into the garden surrounding the synagogue in Goteborg, but they failed to damage the building.

Swedish Prime Minister Stefan Lofven and other top politicians condemned the incidents and authorities increased security around the synagogue and at Jewish centres in Stockholm and Malmo.

"I'm terribly upset over the attack on a synagogue in Goteborg yesterday and calls for violence against Jews at a demonstration in Malmo," Lofven said Sunday. "There is no place for anti-Semitism in our Swedish society. The perpetrators will be held accountable."

He urged "all democratic forces" in Sweden to work together to create "a tolerant and open society where everyone feels safe."

On Saturday, Swedish Foreign Minister Margot Wallstrom tweeted that those who called for Jews to be killed did something "totally unacceptable."

The European Jewish Congress said Sunday it was "unconscionable that Jews are under attack on the streets of Europe" and urged Swedish and other European governments to take "strong punitive action" against perpetrators.

In Nordic neighbour Finland, national broadcaster YLE said police would raise security measures around the Helsinki synagogue.

The American Jewish Committee, meanwhile, condemned a separate protest Friday in Berlin, during which American and Israeli flags were burned in front of the U.S. embassy.

The director of the AJC's Ramer Institute in Berlin, Deirdre Berger, called Sunday for an "unequivocal response" from German politicians, saying "the protests have to be condemned."

Berlin police said 10 people were detained and 12 criminal complaints were filed over the protest of Trump's decision to move the American embassy from Tel Aviv to Jerusalem.

Frank Jordans contributed from Berlin.