A Turkish-German actress will read out Norwegian mass-murderer Anders Behring Breivik's bizarre courtroom speech in German theatres next month in an effort to highlight the widespread prevalence of far-right ideology in Europe.

Swiss director Milo Rau adapted the script of "Breivik's Explanation" for the German stage from an audio recording of the hour-long speech the far-right nationalist gave in April before being sentenced by an Oslo court to 21 years in prison for killing 77 people last year.

Though Breivik's talk of an international underground of killers - latter-day Crusaders he called the Knights Templar - seemed to be mere fantasy, many of his beliefs are to be found within the fold of anti-Muslim, anti-immigrant populists.

"His ideological `manifesto' is a distilled representation of a cultural crisis that pervades the European continent and finds expression in an increasingly xenophobic populism," Kirsten Simonsen, a professor at Denmark's Roskilde University, wrote in "Bloodlands", a 2012 series of essays about Breivik.

Some notions touched on by Breivik in his justification for setting off a bomb in Oslo and shooting dozens of teenagers dead on an island retreat - that Europe and its indigenous cultures are being weakened by immigration and multiculturalism - have been helping reshape right-wing continental politics for years.

The theatre performances in Weimar and Berlin are intended to promote the view that while Breivik's actions were those of a madman, the ideology that drove him is shockingly widespread in democratic societies like Switzerland and Germany, the 35-year-old director told Reuters.

"It's merely a coincidence that Breivik was the one saying it," Rau said. "His words could just as well have come from 60 percent of the Swiss population."

Citing the language of far-right Swiss nationalists who enjoy wide support in his country, Rau added that issues such as a referendum banning the construction of minarets in Switzerland exposed the parallels between Breivik's hate speech and the xenophobia in European society.

Breivik's words will merely be read rather than dramatized and there will be no courtroom scene, Rau said. Turkish-German actress Sascha Soydan was chosen to distance the Breivik "character" and his actions from the ideology that drove him.

"It's not a good speech and it doesn't make for good theatre either," Rau said. "I want to show a text and an ideology, I don't want to depict the person behind them - that's why I opted for this extremely unauthentic portrayal and very dry way of doing it."

Only snippets of Breivik's speech were ever made public during the proceedings in April because judges thought publishing it in its entirety would only provide Breivik with a platform for his xenophobic views.

"There's a reason the speech wasn't allowed to leave the courtroom - so that no one tinkers around with it and makes it seem better than it was," Rau said.

Performances are scheduled to take place in Weimar on October 19 and in Berlin on October 27. A panel discussion will follow both performances.