"With an upsurge in Sweden of violent and anti-Semitic behavior linked to political extremism, the authorities must step up protection around Jewish sites," the congress's president Ronald S. Lauder said in a statement on Tuesday.
"We thank Swedish authorities for their close communication with the Jewish community and their willingness to address these issues."
Lauder's comments come after the Vasa Real high school in central Stockholm, which offers lessons in Jewish and Hebrew, was subjected to graffiti containing swastikas and Nazi messages on Sunday night. The graffiti attack left one parents in tears, and fearing the rise of fascism in Europe.
Police launched an investigation, but the perpetrators remain at large. Members of Sweden's Liberal Party (Folkpartiet) youth wing took matters into their own hands on Monday night and "love-bombed" the school, leaving heart-shaped cut outs and messages of love for the pupils.
"We wanted the pupils at the school to be greeted by love in the morning instead of all the hate they saw on Monday," young Liberal Bawar Esmail told The Local.
The World Jewish Congress is an international organization representing Jewish communities in 100 countries to governments, parliaments and international organizations.
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The Vasa Real school has more than 800 pupils from grades five to nine, when the children are aged between 11 and 15. At high-school level, there are three classes with Jewish children who study the Swedish curriculum but also study Hebrew and Jewish studies, according to the Vasa Real website.