Son of Norwegian princess admits taking cocaine and alcohol before assault on girlfriend

The son of Norway's Crown Princess Mette-Marit has admitted carrying out a cocaine and alcohol-fuelled assault on his girlfriend, in a statement released by Norwegian broadcaster NRK on Wednesday.

Police arrested Marius Borg Hoiby, 27, on August 4 following a night-time row at an apartment in Oslo.

He has been accused of causing bodily harm and injuring a woman with whom he was having a relationship.

According to Norwegian media reports, police found a knife stuck in one of the walls of the woman's bedroom at the apartment.

The day after the incident, the woman received medical treatment but was not admitted to hospital, her lawyer said.

In his statement to NRK, Hoiby said that "something happened that should never have happened."

"I committed bodily harm and destroyed objects in an apartment while under the influence of alcohol and cocaine after an argument," he added.

Hoiby said he had suffered with "mental troubles" and struggled "for a long time with substance abuse".

He said he would seek new treatment and "take it very seriously".

But he added that "the consumption of drugs and my diagnoses do not excuse what happened in the apartment."

"I want to take responsibility for what I did," he said, promising to be frank with police.

Hoiby has already pleaded guilty and says he is ready to serve out whatever sentence is handed down, his lawyer Oyvind Bratlien told Norway's TV2 television.

Hoiby was born in 1997 from a relationship prior to Mette-Marit's 2001 marriage to Crown Prince Haakon, the heir to the Norwegian throne.

While Hoiby was raised by Mette-Marit and Haakon together with his step-siblings, 20-year-old Princess Ingrid Alexandra and 18-year-old Prince Sverre Magnus, unlike them he has no official public role.

The royal family has so far made no comment on the arrest.