Norwegian police said on Saturday that the 27-year-old son of Crown Princess Mette-Marit had been arrested for violating a restraining order.
Marius Borg Hoiby was initially detained on August 4 following a night-time row at a woman's apartment in Oslo and accused of causing bodily harm to the resident, with whom he was having a relationship.
Norwegian media reports said police found a knife stuck into one of the walls of the woman's bedroom at the time.
"At the beginning of September, police received information that Marius Borg Hoiby had, on several occasions, made unwanted contact with the woman, who has the status of victim in the incident," police said in a statement on Saturday.
They "filed a report for reckless behaviour and imposed a restraining order on Hoiby", it said.
They subsequently "received information that Hoiby had violated the restraining order" and he was rearrested late on Friday due to the "risk of recurrence".
Police now suspect Hoiby of crimes against three other victims — domestic abuse of two women and threats to another person.
Hoiby's lawyer Oyvind Bratlien said his client denied the allegations.
"In my 17 years as a defence lawyer, I have never experienced or heard of an arrest on such a flimsy factual and legal basis," Bratlien told broadcaster NRK.
Hoiby was born in 1997 from a relationship prior to Mette-Marit's 2001 marriage to Crown Prince Haakon, the heir apparent to the Norwegian throne.
He and his step-siblings — Princess Ingrid Alexandra, 20 and Prince Sverre Magnus, 18 — were raised together by Mette-Marit and Haakon.
Unlike them, he has no official public role.
