Prosecutors in Norway have charged the son of Norway's crown princess with reckless behaviour and violating a restraining order a month after he went on trial for rape and dozens of other alleged offences.

Marius Borg Høiby was arrested the day before his trial began at the start of February, on suspicion of threats and violence against a woman in his flat in Oslo. Police remanded him in custody for the first four weeks of the trial.

Although allegations of bodily harm and knife threats have been dropped, prosecutors say the 29-year-old has admitted reckless behaviour and violating a restraining order.

He now faces a total of 40 charges and denies the most serious allegations.

Marius Borg Høiby is the son of Crown Princess Mette-Marit and grew up in the royal family, but he is not a member of Norway's royal house. He was four when his mother married Crown-Prince Haakon in 2001.

He has admitted some of the 40 charges against him, but denies four counts of rape which all involve a woman who was either asleep or incapacitated after they had had intercourse.

The latest charges against him relate to a woman from the upmarket Frogner area of Oslo, who he was banned from contacting at the time.

He already admitted violating a restraining order relating to the same woman at the start of the trial and partially admits other allegations that date back to 2024.

Marius Borg Høiby was first arrested after a violent incident at the woman's Frogner flat, and spoke at the time of suffering from mental issues for years.

Although it is unusual for further charges to be added during a trial, state prosecutor Sturla Henriksbø explained that this was possible if the defendant admitted the offences. Reckless behaviour can command a jail term of up to two years in prison.

By Tuesday the trial at Oslo District Court was 17 days into the 28 days allocated for the case, which is taking place amid tight restrictions requiring no images of either the defendant or the four women he is alleged to have raped.

The only woman who can be identified is a former girlfriend, Nora Haukland, who he denies abusing. She has already given evidence to the court that he kicked, punched and choked her during their relationship between 2022-23.

Last week an audio recording was played to the court of an argument in which Marius Borg Høiby could be heard hurling abuse at Ms Haukland, a Norwegian influencer with more than 100,000 followers on Instagram.

He denies being violent and his defence counsel says his ex-girlfriend did not in any way "live in a regime of fear".

During Tuesday's proceedings, the court heard from Nora Haukland's former boyfriends, including one who spoke of their "peaceful break-up" and his respect for her, and another who described their relationship as turbulent.

If found guilty of the more serious charges he could spend at least 10 years in jail.