A video of the incident in the town of Brunnen in the canton of Schwyz shows a group of around a dozen hooded figures carrying burning torches along a street.

The passer-by who captured the video said he was shocked. “That is definitely taking it too far,” he told Swiss news site 20 Minuten.

While many things are acceptable during carnival “there have to be limits”, he said.

Police are now investigating footage and photos of the incident, Swiss news agency SDA reported.

But lawyer and racism expert Daniel Kettiger told 20 Minuten. said it would be difficult to establish members of the group had been guilty of racial discrimination in the current case.

This was because no specific race or ethnicity had been directly and demonstrably targeted by the group and because their appearance had come during the context of carnival celebrations when there is a relatively high tolerance for satire.

But Kettiger said the case would be very different if the group had marched past an asylum home where most of the residents were black.

“That would be violation of anti-racism laws and punishable by law,” he said.