King Harald of Norway has been taken to hospital for treatment in connection with a blood disease, the palace has said.

Harald, who is 89, was admitted to the National Hospital on Monday afternoon, the royal palace said in a statement.

“The King has been treated with cortisone for the blood disease hemolytic anemia in recent weeks,” the palace said in a statement. “This has led to fluid accumulation in the body that requires treatment in hospital.”

The statement pointed out that the king has been on sick leave for two weeks.

“His royal highness the crown prince is regent during this period,” said the statement, referring to Harald’s son, Haakon.

Harald has been in and out of the hospital several times in recent years.

In February, he was admitted to a hospital in Spain’s Canary Islands during a winter vacation. He was treated for a skin infection at the time.

Two years ago, the king fell ill during a private vacation with the queen in Malaysia and received a temporary pacemaker there. Harald returned aboard a medical airplane to Norway, where he was fitted with a permanent pacemaker.

Harald has been Norway’s monarch since 1991.