Members of Germany’s neo-Nazi National Democratic party (NPD) were forced to cancel a protest in the south-west city of Freiburg after they got on to a train to Mannheim by mistake.

Police said they had received word at around noon on Saturday that the demonstration, which had been planned for 2.30pm outside Freiburg’s administrative court, had been called off.

The group of fewer than 20 NPD members became confused after police prevented them from boarding the Freiburg train because it was full of far-left “ultra” football supporters on their way to a Bundesliga match, police spokesperson Dirk Klose told the Guardian.

To prevent any trouble, the police told them to take another train to the Black Forest city, but the NPD members simply got on the next train from the same platform – apparently without checking the destination notice.

“I don’t know how it happened, but the NPD phoned us up and said they’re not coming, and that they’re on a train to Mannheim,” said Klose. “The NPD is now saying they went to Mannheim deliberately.”

Meanwhile, a handful of anti-fascist counter-demonstrators had already gathered in anticipation in Freiburg, along with a police contingent to keep the two sides apart.

The neo-Nazis had intended to demonstrate in solidarity with a woman who had allegedly been refused permission to take the final exam for a public management studies qualification because of her allegiance to the NPD. She had written a letter of complaint to the Badische Zeitung.

The cancellation was greeted with relief in Freiburg. “We didn’t miss them,” said the town’s deputy mayor, Otto Neideck.