Norway's Crown Princess Mette-Marit has completed a successful lung transplant operation in Oslo, according to statements from the royal household.

The 52-year-old royal received a diagnosis of pulmonary fibrosis in 2018, though her health has deteriorated markedly over recent months.

Lung specialist Are Holm remarked in the official palace statement that developments have been encouraging thus far.

He noted that Mette-Marit will stay in hospital for several weeks of monitoring, following standard protocol for transplant patients.

Prince Haakon plans to revise his official engagements to provide support during her recovery, the palace confirmed.

Royal historian and commentator Ole-Jørgen Schulsrud-Hansen described the transplant as very welcome news for the Norwegian royal family and the country overall.

He observed that this step removes one of the gravest challenges to the Crown Princess improving her health, and many feel a sense of relief at the positive outcome.

Mette-Marit, who wed Haakon in 2001, was diagnosed in 2018 with a rare pulmonary fibrosis variant that leads to breathing problems.

As her condition advanced she reduced her public duties, and earlier this year specialist Holm described the decline as substantial and dangerous.

Her most recent public appearance occurred on 17 May, at which time she relied on a nasal tube linked to an oxygen supply.

The palace placed her on the transplant waiting list twelve days ago, with physicians noting that those added to the list generally have roughly one year of life expectancy remaining.

Holm stressed that priority always goes to the most severely affected patients.

He also underlined that post-transplant recovery demands great care, including lifelong use of immunosuppressive drugs.

Statistics indicate that one in eight recipients of a donor lung do not survive the first year, while around half remain alive after ten years.

The lung transplant adds to a challenging period for the Norwegian royals, following January document releases that detailed Mette-Marit's repeated contacts with the late sex offender Jeffrey Epstein.

She issued an apology to Norway's king and queen regarding her three-year association with Epstein, acknowledging errors in judgment, and stated in a national television interview that she regretted ever meeting him.