The Norwegian royal family issued a statement on the 28th announcing that King Harald V has passed away at the age of 89.
The 53-year-old Crown Prince Haakon will automatically succeed to the throne.
The statement said: “It is with deep sorrow that we announce that His Majesty King Harald has passed away today. King Harald died peacefully at Oslo University Hospital at 6:35 a.m. on Friday, August 28.”
The day before, the Norwegian royal family announced that Harald V had been hospitalized due to complications caused by a blood disease, with his condition deteriorating and becoming extremely critical.
Queen Sonja of Norway and the crown prince couple canceled all engagements. They spent most of the day on the 27th at the hospital, accompanying the King.
Footage released by Norwegian media showed virtually all members of the royal family taking turns keeping vigil at the King's bedside.
As Europe's longest-reigning monarch, King Harald V suffered from hemolytic anemia, a blood disease that causes abnormally rapid destruction of red blood cells. He had been receiving treatment at Oslo University Hospital since August 17.
King Harald V ascended the throne in January 1991. In recent years, he has been hospitalized multiple times due to health issues. During his sick leave, Crown Prince Haakon has served as regent, temporarily performing the duties of head of state.
After news of the King's deteriorating health emerged, many people gathered in front of the Royal Palace and laid flowers.