Mette-Marit appeared to be in good spirits but was assisted by nasal prongs for oxygen support during the engagements. The crown princess looked elegant in a navy blazer, khaki trousers and a white top underneath.

Guri Varpe, Head of Communications of the Royal House of Norway, told Norwegian outlet TV2: “As is known, the Crown Princess has the chronic disease pulmonary fibrosis.

“As we communicated in December, there has been a clear negative development in the Crown Princess's health recently, and preparations have begun with a view to an assessment for a lung transplant.

“The Crown Princess has an increasing need for tailored training, rest and recovery, and her official program is adapted to her health condition.”

Her last public appearance before today was Mette-Marit’s on January 28, just a few days before the release of the Jeffrey Epstein files, some of which mentioned her.

She was previously snapped out and about with her husband, still receiving oxygen support, last month.

The Epstein documents, which include email exchanges, showed that Mette-Marit borrowed an Epstein-owned property in Palm Beach, Florida, for several days in 2013.

The Crown Princess expressed her “profound regret” and apologised for her friendship with Epstein.

Being mentioned in the Epstein files does not indicate wrongdoing.

Meanwhile, her 29-year-old son, Marius Borg Høiby, is on trial facing 38 charges, including rape, sexual assault and bodily harm.

He has pleaded not guilty to the four charges of rape. However, he pleaded guilty to several driving offences, to an aggravated drugs offence and breaking a restraining order, and “partly” to threats and aggravated assault.