The eldest son of Norway's Crown Princess Mette-Marit has been arrested on suspicion of rape, police have said.
Marius Borg Hoiby is the stepson of the heir to the Norwegian throne, Crown Prince Haakon, and the son of Princess Mette-Marit from a previous relationship.
He has no royal title or official duties.
Borg Hoiby was arrested late on Monday in Oslo on a preliminary charge of having had "sexual intercourse with someone who is unconscious or for other reasons unable to resist the act".
A preliminary charge comes before a formal charge and allows authorities to detain suspects during an investigation.
Police did not say when the alleged rape occurred.
Norwegian media reports that Borg Hoiby has denied the accusation.
Hege Salomon, the lawyer for the woman who was allegedly raped, said "she is having a hard time".
She told Norwegian broadcaster NRK that police, not the woman, had brought the case. The woman was not identified.
The royal palace has not commented.
On August 4, police officers responded to a disturbance in central Oslo and briefly detained Borg Hoiby.
He faced preliminary charges of bodily harm and criminal damage and was released.
More preliminary charges have since been filed against Borg Hoiby, including violating several restraining orders and driving without a valid driver's licence.
The case was top news in Norway, where the royals are popular.
Borg Hoiby, 27, lives with the royal couple and their two children, Princess Ingrid Alexandra and Prince Sverre Magnus.
