School pupils in Germany are being urged by the far-right Alternative für Deutschland party (AfD) to denounce teachers who express a political opinion.

Neutral Schools, an online portal, has been launched as a pilot project in Hamburg and the AfD has announced plans to roll out the scheme across the country.

Pupils have been invited to post anonymous complaints on the site about teachers they believe are breaking neutrality rules and criticising the AfD.

The AfD, the strongest opposition in the Bundestag where it has sat since elections last year, said the initiative aims to “strengthen a democratic and free discourse” in schools, as well as highlight the neutrality code and give pupils advice on how to act if they believe a teacher is breaching it.

The platform has sparked heated debate and the party is facing growing calls from teachers and cultural figureheads to end the project, with many accusing the AfD of adopting tactics used during the Nazi and Communist eras.

Christian Piwarz, the culture minister in the state of Saxony, said the AfD was breeding a “despicable mindset of snoopery as was known from the times of the Nazi dictatorship or the Stasi [the East German secret police]”.

Heinz-Peter Meidinger, the president of the German Teachers Association, called the project “an attempt to exploit children and young people and to instigate the practice of denunciation”.

But the party, which rose to power on its anti-immigrant stance, winning 90 parliamentary seats at the last election, has hit back. It says its website has nothing to do with denunciation. According to Bernd Baumann, a leading member of the AfD’s parliamentary group, it is a chance to address the considerable evidence the party said it had collected, showing that schools were often drawing “a very severe picture of the AfD as radical, inhuman and cold”.

The party has encouraged pupils to look out for “cloddish AfD bashing”, including those wearing bags, badges or T-shirts bearing the slogan “FCK AfD”, as well as pointing out anything that might be recognisable as political indoctrination.

Uwe Böken, a headteacher from Geilenkirchen, said he was denounced by the AfD after he invited the surviving member of a girls’ orchestra that was imprisoned in Auschwitz to talk to his school. Böken voiced his concerns during her visit that people with far-right views were sitting in the German parliament for the first time since the second world war.

A disciplinary complaint was brought against Böken by the AfD. Even before it was ruled that Böken had not broken the neutrality code, he was denounced by party members across social media.

“What’s happening with this portal is pure denunciation,” Böken told the broadcaster Deutschlandfunk. Böken has taken his case up with the justice ministry. “You just have to look at a history book or also at the present day, to recognise this as something belonging to systems with a clear totalitarian character,” he said.