Norway's King Harald V, aged 87 and in poor health, is "improving" from an infection that forced him to be hospitalised while on holiday in Malaysia, according to his office.

The king will remain in hospital on the island of Langkawi and it is not yet known when he will return home, the Royal House of Norway said in a statement Wednesday.

The king's "personal physician is in Langkawi and confirms that the king is improving from his infection. His majesty is well taken care of at the hospital and is receiving good treatment," the statement said.

"His majesty will remain at the hospital for a few more days. No decision has been made regarding his return home," it added.

Outside the Sultanah Maliha Hospital in Langkawi a guard ushered media away from the facility as cars and motorbikes entered and left the compound, according to an AFP journalist.

Malaysian state news agency Bernama said the king was staying in the hospital's royal suite, citing unnamed sources.

Malaysian health ministry officials and the Norwegian embassy in Kuala Lumpur have declined to comment.

The king's next work commitment was scheduled for March 8 when he was set to meet the Norwegian government cabinet in Oslo, according to the Norwegian royal court's calendar.

Those monthly meetings -- known as the Council of State -- are where new laws are agreed and signed off by the country's monarch and premier.

Europe's oldest ruling monarch, who turned 87 in February, needs crutches to get around and has suffered from a series of ailments and illnesses in recent years, including heart surgery and various respiratory problems.

In January, he was ill with a respiratory infection just a few days after dismissing speculation that he might abdicate, following the lead of distant cousin Queen Margrethe II in Denmark.

"I stick by what I've always said, that I swore an oath to the Storting (parliament) and it is for life," said Harald, quoted by Norwegian media.

In his absence, Crown Prince Haakon, 50, steps in as regent.