A sign in German reads: 'Careful, High-Voltage, Danger' at the former electrified fence at the Auschwitz concentration campGetty

A school in California has cancelled a class assignment in which pupils were asked to debate whether or not the Holocaust actually occurred.

The assignment at Southern California's Rialto Unified School District aimed to teach eighth-graders the nature of propaganda.

The assignment asked pupils whether the Holocaust was an actual event or was instead a "propaganda tool that was used for political and monetary gain".

After the school received a series of complaints – and even a death threat, according to the Rialto police department – it confirmed it will no longer be asking the pupils to write an essay debating the existence of the Holocaust.

The school added it will ensure all future research assignments will not reference the possibility of the Holocaust "not occurring".

"The Holocaust should be taught in classrooms with sensitivity and profound consideration to the victims who endured the atrocities committed," San Bernardino County district spokeswoman Syeda Jafri said. "We believe in the words of George Santayana, those who cannot learn from history are bound to repeat it."

One of those who was critical of the assignment was Rabbi Abraham Cooper, the associate dean of Jewish human rights organisation Simon Wiesenthal Center.

Cooper said while he thought it was a good idea to teach the children about propaganda, it may have been more beneficial to have them meet with some Holocaust survivors to counteract against those who believe it never existed.

"Whatever (the district's) motivation, it ends up elevating hate and history to the same level," he told FoxNews. "We should train our kids to have critical thinking, but the problem here is the teacher confused teaching critical thinking with common sense."

Discussing the death threat – directed towards Jafri and the school's interim superintendent Mohammad Islam, Rialto police captain Randy De Anda said: "We believe he [the caller] is a white male in his 30s. He did give us a name, but we haven't confirmed it yet so we don't know if he's a previous student."

More than 11 million people, including six million Jews, where killed during the Holocaust, which ended in 1945 following the defeat of Nazi Germany in World War II.