In addition to the so-called bonus prince, Harald's children and grandchildren, Queen Mette-Marit and Queen Sonja were at the coffin.
Marius Borg Høiby, who is Mette-Marit's son from a previous relationship and not part of the royal family, was sentenced in June to four years in prison for, among other things, rape and is being held in custody with ankle shackles.
The country's prosecutor's office has approved that he may participate in King Harald's funeral on September 9 and certain other formal events before then, Norwegian media report.
Starting Tuesday, the public will have the opportunity to say goodbye to the king at the coffin in the castle chapel.
King Harald died last Friday, aged 89.
