AALST, Belgium — In Aalst, a small city northwest of Brussels, the Carnival parade is the main event of the year, where everyone and everything is mercilessly mocked, and drunkenness and a lack of taste are part of the mix.

But this year, floats that the townspeople regarded as the customary shameless satire of their famed Carnival set off an uproar. One float in the parade on Sunday carried two giant figures of Orthodox Jews, with side curls and grotesquely large noses, sitting on bags of money. Another group paraded in the white hoods and robes of the Ku Klux Klan.

At a time when expressions of anti-Semitism and racism are on the rise in many countries, images of the event quickly spread around the world, unleashing accusations of bigotry and historical ignorance.

Some critics began an international campaign to push Unesco, the United Nations’ cultural organization, to withdraw its official recognition of the Aalst Carnival — one of Europe’s largest — as a “cultural heritage” event.