Norway's King Harald has been hospitalised in Malaysia with an infection, the Norwegian royal household said on Tuesday.

The 87-year-old monarch is on a private trip to the South East Asian country.

"His majesty the king has fallen ill during his holiday stay in Malaysia, and is hospitalised there, with an infection. The king receives good care from both Malaysian and Norwegian medical personnel," the royal household said in a statement.

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

Crown Prince Haakon presides in his father's absence. (Reuters)