Laying flowers and embracing, thousands of people gathered in Oslo on Friday to pay their respects to Norway's King Harald, who died Friday aged 89 after a reign of three and a half decades.

Harald's 53-year-old son immediately succeeded him on the throne, announcing he would reign under the name King Haakon VIII.

Haakon takes over a monarchy long hailed for its modernity and modesty, but beset by a string of scandals in recent years.

A motor procession with King Harald's casket left Oslo University Hospital on Friday evening, taking the late monarch on the 20-minute ride to the royal palace, televised images showed.

Members of the public braved the rainy weather to line the streets to catch a glimpse of the procession, which included the royal family. 

King Haakon VIII had arrived at the palace just before lunch with his 22-year-old daughter Ingrid Alexandra -- the new crown princess -- to formally inform the government of his father's death.

In a statement, Haakon thanked "the government and Norwegian people for their support and sympathy for the Royal Family at this time".

"An era has ended. A new one begins. The king is dead. Long live the king," Prime Minister Jonas Gahr Store said in a speech shortly after meeting the new monarch.

"We will remember King Harald for his love for his people, for his humour and warmth, and for his unwavering faith in us," he said.

Store was later seen laying down flowers in front of the palace.

Norway's parliament said the new monarch would take an oath of allegiance in its main chamber on September 1.

The government announced a period of national mourning until Harald's funeral, the date of which is yet to be set.

'A king of his time'

Europe's oldest reigning monarch, King Harald had been in hospital in Oslo since August 17, suffering from haemolytic anaemia, a condition caused by an abnormally rapid destruction of red blood cells that leads to fatigue and shortness of breath.

Store said Harald, who ascended to the throne in 1991, was "a king of his time and for his time", noting that he accompanied Norway through decades of enormous change during which the country "grew richer, we became more numerous, and we became more diverse".

Thousands of Norwegians massed outside the palace in Oslo as it began to rain. They laid down mountains of flowers, cards and red, white and blue national flags, and many hugged and held each other.

"He was the king of the people," mourner Kristoffer Hamre told AFP.

The palace lowered its flag to half-mast after Harald's death was announced, but raised it again after Haakon arrived for the meeting with the government.

Another flag on the royal balcony and those at other official buildings will remain at half-mast until after Harald's burial.

Like many mourners, Vigdis Haug, 65, said she valued Harald's ability to unify people.

"I think he has been such a down-to-earth king who has cared about all of us, and the words he always uses when he gives a speech are so wise and so valuable," she told AFP.

Harald was widely seen as the embodiment of an open and tolerant Norway.

Many of those AFP spoke with pointed in particular to his speech after neo-Nazi Anders Behring Breivik killed 77 people in twin attacks on July 22, 2011, in Norway's worst massacre since World War II.

"He was someone who always seemed to find the words that brought us together and gave us a sense of security," Caroline Vagle, a reporter for magazine Se og Hor, told AFP.

Tributes poured in from leaders around the world, including those of France, Germany, India, Israel, Italy, Jordan and Ukraine, as well as the royal houses of Europe.

Turbulent year

Harald faced mounting health problems in his final years, forcing him to scale back his official schedule.

But he ruled out abdicating, arguing that he took a lifelong oath before the Norwegian parliament. 

The past year has been a turbulent one for the Norwegian royal family.

In addition to his own health struggles, his wife Queen Sonja, also 89, was briefly admitted to hospital in May due to heart problems. 

Haakon's wife Mette-Marit is under scrutiny for her ties to the late US sex offender Jeffrey Epstein.

In June, Mette-Marit's son from a relationship prior to her marriage to Haakon, Marius Borg Hoiby, was sentenced to four years in prison for two rapes.

Suffering herself from a serious lung disease, Mette-Marit, 53, had to undergo a lung transplant in July.