In an interview in the Sunday edition of the Tagesspiegel newspaper, Katharina reiterated her pledge to hand over the private papers of her father, Wolfgang Wagner, to the Bavarian State Archive, with the aim of shedding new light on the festival's history.
"This will mean that historians and scholars can have access to this material," she said.
But she gave little hope that the potentially more explosive private correspondence between the Wagner family and Hitler would similarly be made available to the public anytime soon.
"And all of their heirs must be in agreement. If even just one says 'No', then I can't do anything about it, no matter how outrageous I might find it," she said.
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Katharina Wagner and her half-sister Eva Wagner-Pasquier took over the running of the Bayreuth Festival from their father Wolfgang Wagner in 2008.
And they have come under heavy pressure since to open up the festival archives, much of which is still under lock and key, so as to be able to shed light on Bayreuth's close ties with the Nazis.
Winifred was a devout Nazi who referred to Hitler as "Unser seliger Adolf" (Our blessed Adolf). Her children -- among them Wolfgang and Wieland who relaunched the festival after the war -- affectionately called the Nazi leader "Uncle Wolf".
In an interview with AFP, Katharina's and Eva's brother Gottfried called for the immediate publication of Winifred's correspondence with Hitler, which he claimed was being held back by his cousin Amelie Lafferentz "without any legal basis whatsoever.