An 87-year-old grandmother has been sentenced to 10 months in jail by a German court for the crime of Holocaust denial.

Ursula Haverbeck, nicknamed Nazi-Oma (Nazi grandma), was sentenced after declaring Auschwitz has not been “historically proven” to be a death camp.

“[That is] only a belief,” she said.

Haverbeck is a noted Holocaust denier who has chaired a Nazi propaganda center that was shut down in 2008.

In April, she appeared on television, declaring, “The Holocaust is the biggest and most sustainable lie in history.”

When asked in court if she actually made the claim, Haverbeck replied, “Yes, I said that.”

Judge Bjoern Joensson reportedly said at one point during the hearing that “it is pointless holding a debate with someone who can’t accept any facts.”

“Neither do I have to prove to you that the world is round,” he said.

The ruling came down Thursday, with Joensson adding, “It is deplorable that this woman, who is still so active given her age, uses her energy to spread such hair-raising nonsense.”

“She is a lost cause.”

Far right supporters waited outside the chamber during the trial, erupting into applause as Haverbeck left the courtroom.

Holocaust denial is a punishable offense in Germany, as it is across much of Europe.