Norway's Crown Princess Mette-Marit has given a profound apology to Norwegians for her friendship with late sex offender Jeffrey Epstein, after it emerged they had exchanged messages for three years.

I also apologise for the situation in which I have placed the Royal House, especially the King and Queen, she said in a palace statement after days of mounting pressure to address the issue.

Harald V and Queen Sonja, who are both 88, have not commented on the revelations.

The King met Prime Minister Jonas Gahr Støre on Friday, alongside Crown Prince Haakon, who told reporters later that his wife wanted to speak: But right now she can't, and I also tell her she is not allowed to.

Hundreds of emails from 2011-14 involving Epstein and the crown princess came to light in the cache of files published by the US justice department a week ago.

Some of the exchanges apparently involve plans to meet in person, and reveal she spent four days at Epstein's Palm Beach house in Florida while he was not there.

The warm nature of the correspondence has come as a shock to Norwegians, and she appears to have been aware he had already served a jail term in 2008: Googled u after last email, she wrote in October 2011. Agree didn't look too good.

Although an initial statement was released last Saturday, in which the crown princess expressed regret and admitted poor judgement, the palace had been pressed to provide further details of how well she knew Epstein.

In a statement on Friday, the palace said the crown princess was deeply saddened that she had failed to realise early enough what kind of person he was.

She wanted to provide a more detailed explanation but was in a very difficult situation and needed time to gather herself.

It is important for me to say I am sorry to all those I have disappointed. Some of the content in the messages between Epstein and me does not represent the person I want to be.

Mette-Marit already had a four-year-old boy, Marius Borg Høiby, from an earlier brief relationship when she married Norway's Crown Prince Haakon in 2001.

His mother has not commented on the trial but Crown Prince Haakon told reporters in Oslo there was a lot going on in his family and the most important thing in the past few days has been to take care of the flock.

We support Marius in the situation he is in. We look after the other children as well... They also need to be cared for, and I have to make sure to take care of the crown princess, he said.

Mette-Marit is also extremely unwell with pulmonary fibrosis and her doctors are preparing to put her on a list for a lung transplant.

Giving evidence in court on Wednesday, her son initially struggled to compose himself, holding back tears as he complained of being hassled by the press since he was three years old.

If found guilty by the three judges at Oslo district court, he could face a jail term of at least 10 years. Two days before the trial began, he was arrested for a fourth time on Sunday, on suspicion of assault, wielding a knife and violating a restraining order.

When approached by the BBC, the palace said it did not wish to comment on the matter.