Sweden's Crown Princess Victoria was allegedly sexually harassed by Jean-Claude Arnault, the French photographer at the centre of the crisis roiling the Swedish Academy.
According to the Svenska Dagbladet newspaper, three sources said they witnessed Arnault groping the then 27-year-old Crown Princess's bottom at an event put on by the body, which awards the Nobel Prize for Literature.
The Swedish writer Ebba Witt-Brattström, one of those present, told the Daily Telegraph that Arnault had approached Victoria unexpectedly.
"He came lurking from behind and I saw his hand land on her neck and go downward. It was all the way down," Witt-Brattström said.
Victoria's female Adjutant, a uniformed aide, had then leapt to her rescue, she said.
"She just flew herself on Arnault. She grabbed him, and 'whop', he was gone. The Crown princess turned in surprise. I guess she had never been groped. She just looked like 'what?'"
The Academy was thrown into crisis in November when 18 women came forward to say Arnault had groped or harassed them at Forum, the cultural centre he ran, or at Academy-owned apartments in Stockholm and Paris.
Arnault is married to the poet Katarina Frostenson, one of the Academy's members.
Arnault's lawyer Björn Hurtig said: "My client most strongly denies these allegations. He claims that these malicious rumours serve a single purpose; to blacken his name and damage him."
Margareta Thorgren, press officer at the Swedish Royal Court told Svenska Dagbladet: "We can't comment on that particular information."
She said, however, that the court supported the #MeToo movement and found the claims against Arnault "frightening".
If proved true, the new accusation will make it harder for Horace Engdahl, Witt-Brattström's ex-husband and the Academy's former permanent secretary, to continue to maintain that he had been unaware of Arnault's reputation as a serial harasser.
Witt-Brattström, now a literature professor at the University of Helsinki, said that Engdahl, herself, King Carl XVI Gustaf, and two other academy members had been standing in a circle with the Crown Princess when Arnault struck.
According to Witt-Brattström, at their next visit in 2006 Engdahl was instructed by the Swedish Court to ensure that the Crown Princess was never left alone with Arnault.
Since the accusations against Arnault came out in November, six Academy members have vacated their seats over the scandal.