BERLIN — The attacks in Oslo on Friday have riveted new attention on right-wing extremists not just in Norway but across Europe, where opposition to Muslim immigrants, globalization, the power of the European Union and the drive toward multiculturalism has proven a potent political force and, in a few cases, a spur to violence.

The success of populist parties appealing to a sense of lost national identity has brought criticism of minorities, immigrants and in particular Muslims out of the beer halls and Internet chat rooms and into mainstream politics. While the parties themselves generally do not condone violence, some experts say a climate of hatred in the political discourse has encouraged violent individuals.

“I’m not surprised when things like the bombing in Norway happen, because you will always find people who feel more radical means are necessary,” said Joerg Forbrig, an analyst at the German Marshall Fund in Berlin who has studied far-right issues in Europe. “It literally is something that can happen in a number of places and there are broader problems behind it.”