Norway’s King Harald V, 89, is in an “extremely serious” condition after his health deteriorated while he was being treated at Oslo University Hospital. Europe’s oldest reigning monarch has been in hospital since 17 August with haemolytic anaemia, later complicated by a bacterial bloodstream infection.

The worsening condition prompted Queen Sonja and Crown Prince Haakon, who is serving as regent, to cancel their official engagements and go to the King’s bedside, alongside other members of the royal family.

The news also prompted an outpouring of public support in Oslo. Hundreds of people gathered outside the Royal Palace, where they laid flowers, lit candles and left handwritten messages and drawings for the King. Similar gatherings were reported in other Norwegian cities as people waited for further updates on his health.

The deterioration also prompted senior government figures to change their plans. Prime Minister Jonas Gahr Støre cancelled a planned trip to Germany, saying he stood with the country in sending his thoughts to the King and the royal family. Parliament Speaker Masud Gharahkhani also cut short a visit abroad to return to Norway.

Harald has been Norway’s king since 1991 and has faced a series of health problems in recent years, including surgery to fit a permanent pacemaker. He has reduced his official schedule but has repeatedly ruled out abdication, saying the oath he took before Norway’s parliament was a lifelong commitment.