The son of Norway's crown princess has begun giving evidence at his trial for rape and more than 30 other alleged offences.

Marius Borg Høiby, 29, looked overwhelmed by the occasion, his voice quivering as he paused several times to take off his glasses and wipe his eyes.

Choking back tears, he said it was very difficult to talk, and complained of being followed by the press since he was three years old.

He denies four allegations of rape as well as other serious charges against him.

He was giving evidence after the first woman he is alleged to have raped told the court she believed she had been drugged during an "after-party" in the basement of his parents' house in December 2018.

The woman, who cannot be named for legal reasons, spoke of her sense of "betrayal and shock" after she was shown videos by police allegedly of him sexually assaulting her shortly after they had had brief, consensual sex.

She had already spoken of a "black hole" in her memory. She had told the court behind closed doors she had no recollection of what happened.

The 29-year-old defendant, who was born four years before his mother, Mette-Marit married Norway's Crown Prince Haakon, is not a member of the royal family or a public figure.

During his first appearance in court on Tuesday, he was seen shaking, and he is understood have had hospital treatment overnight, rather than returning to custody.

Appearing in court on Wednesday, he took a seat and after several minutes in which he looked overcome by the occasion, he regained his composure and told the court he had had a lot of sex, drugs and alcohol because he had an extreme need of validation.

"I am known for being my mother's son. Nothing else. I have had an extreme need for validation," he told the three judges.

His trial coincides with a tense moment for his mother, after she was found to have exchanged hundreds of messages with the late US sex offender Jeffrey Epstein over a three-year period.

The royal palace said on Wednesday that Crown Princess Mette-Marit had postponed a private trip "until further notice", without giving further details.

However, the storm of criticism over the unguarded, warm tone of the exchanges has heaped pressure on the royal house, when Mette-Marit is also seeing her son on trial for rape.

She has expressed regret and poor judgement over the correspondence.

The defendant, wearing a dark turtle-neck woollen sweater with a zip, looked straight at the three judges who were sitting about 10m (30ft) away at the front of the court.

Although he had notes, he did not look down at them, speaking for about half an hour without interruption.

He sat, not looking to his left where two of the women he is alleged to have raped listened to his evidence a short distance away. He spoke of how he met the first woman he is alleged to have raped, talking about how they had met at a party, and he had taken cocaine for the first time.