The 87-year-old received a temporary pacemaker on Saturday, after being hospitalised for an infection while on a private trip in the resort island of Langkawi.

“The infection has recently come more under control. The king has a low heart rate and will need a permanent pacemaker,” the court said in a statement.

The time for inserting the device will be determined once the king’s infection has healed entirely, the court said, adding that the monarch would most likely remain in hospital until next week.

King Harald, Norway’s ceremonial head of state since 1991, is Europe’s oldest living monarch. He has repeatedly been hospitalised with infections in recent years and has previously undergone heart surgery.

Crown Prince Haakon carries out his father’s duties in the king’s absence.