“His condition, given the circumstances, is satisfactory,” a statement read.

The king – the oldest of Europe’s sovereigns – marked his latest birthday on Saturday. He was admitted to the Hospital Universitario Hospiten Sur on the island.

His personal doctor was due to travel to Tenerife to support the Spanish health services, with an initial health report due on Wednesday.

He and his wife, Queen Sonja, 88, are currently wintering on Tenerife, the largest of the Canary Islands off the coast of west Africa.

Harald experienced similar health problems two years ago while on holiday in Malaysia.

Following that infection, he had a pacemaker fitted and scaled back his official engagements.

Since ascending to the throne in 1991, Harald has always ruled out abdicating despite his frail health, arguing that he took a lifelong oath before the Norwegian parliament.

His latest health issues come with the monarchy mired in scandals.

Crown Princess Mette-Marit, who married Harald’s son, Crown Prince Haakon, in 2001, appears multiple times in documents linked to Jeffrey Epstein, revealing an unsuspected closeness with the late American sex offender.

Mette-Marit’s son from a previous relationship, Marius Borg Hoiby, is currently on trial on 38 charges in Oslo, including four rapes and assaults.

The 29-year-old, who is not a member of the royal family, denies the most serious charges.

The popularity of the Norwegian royal family has fallen to its lowest level, according to a poll published on Saturday by public broadcaster NRK.

Only 60 percent of the population supports the monarchy — 10 percent less than the previous month. NRK said the support “has never been so low”.

Harald himself, however, is a unifying figure and remains extremely popular, scoring 9.2 out of 10, the survey suggested.