An entire high school class in Germany is being investigated after the teenage pupils allegedly started greeting each other with 'Heil Hitler' and communicating in Nazi slogans.

Parents and authorities are horrified after it emerged that some of the 29 student have been swapping Nazi sayings and slogans throughout the school day on instant messaging-app WhatsApp.

Photos of students aged 14 and 15 at a school near Leipzig in east Germany show them giving Nazi salutes and wearing Hitler moustaches.

Horrific: A photograph of one of the male students in class 9A at the Landsberg School near Leipzig, east Germany, shows him raising his right arm in a Nazi salute

Students in class 9A at the Landsberg Gymnasiums near Leipzig regularly made anti-Jewish slurs on the messaging app, while praising Hitler as a 'great man,' local media reported.

Photos appeared in Germany's biggest newspaper BILD on Tuesday showing individuals giving the Hitler salute. One boy who was wearing a stuck-on Hitler moustache had his face blacked out.

One of the messages from a student made a Holocaust joke that read: 'Why did Hitler kill himself? The Jews sent him the gas bill.'

Parents of students in the class are outraged at the reports, saying it is unlikely an entire class of teenagers would be involved and that the media is tarnishing all 29 students with the same brush.

Eli Gampel, 54, who has a son in the class, said: 'These discussions about the Nazi class from Landsberg are a load of rubbish. I thought it was a bad dream when I opened newspapers and read the article.'

Fear: Parents are in shock after media reports that all 29 students in the class, boys and girls ages 14 and 15, appear to have been engaging in the behaviour on WhatsApp

Disgusting: Screen grabs from the WhatsApp conversations see students use 'Sieg Heil' phrase, right

Photos of 14 and 15-year-old students show them giving Nazi salutes and wearing Hitler moustaches

Gampel, the former head of the local Halle Jewish Community, said his son had experienced harassment at the school.

'My son told me that someone had stuck a far-right NPD [National Democratic Party] sticker on his jacket. It was well known, it seems, that he was Jewish.'

'I have made a formal complaint with police for an investigation, but on the other hand it would definitely be the wrong thing to simply accuse the entire class and tar them with the same brush.'

He said: 'Even after I read about it, I found it difficult to get him to talk about what went on. It was only through a lengthy discussion that he admitted what was in the newspaper article was essentially true.'

A spokesman the state educational affairs minister in Saxony-Anhalt said: 'I am shocked. If this is true there can only be one way forward here: zero tolerance!'

The WhatsApp exchanges have been handed over to police and prosecutors.

In shock: The school, Landsberg Gymnasiums near Leipzig, where the teenagers all study

The school headmaster Lutz Feudel said the entire school had been shocked, and that the secret Nazi sympathisers were confined to one class.

Getting to the bottom of how it happened would be difficult because the autumn break had already started, he said.

He said the parents of two of the children involved had been invited to a discussion together with their children, but that a third who they wanted to speak to was on holiday in Spain.

He said he did not want instantly accuse the children, saying: 'Breaking taboos is part of young adulthood. I don't believe that they wanted to actively promote neo-Nazi ideology.'

Any public display of Nazi symbols, salutes or phrases is a strictly forbidden act in modern-day Germany, and a first offence can carry a penalty of up to six months in jail.

All the class students, like all children in Germany, have visited a Nazi concentration camp and regularly learn about the excesses of the Third Reich in classes.

Police said two teenagers are under investigation while a more extensive probe gets underway next week when the school reopens after the half-term break.

Media reports said a psychologist has been arranged to meet with the children, teachers and their parents next week to try to get to the bottom of the fascination with Nazism.

Neo-Nazi groups significantly stepped up their recruitment of children in recent years.