Leipzig - Norway's Crown Princess Mette-Marit (51) has canceled her planned appearance at the Leipzig Book Fair for health reasons.

The royal lady from the Norwegian royal family is suffering from chronic pulmonary fibrosis, which is why she has been on sick leave for two weeks, the royal family announced on Monday.

The wife of Crown Prince Haakon (51) was actually expected in Leipzig this Thursday to represent this year's guest country at the book fair.

She was to open the Norwegian stand with, among others, author Karl Ove Knausgard (56) and the Minister of Culture and Equality Lubna Jaffery (44).

At the beginning of March, it was last reported that the 51-year-old's daily routine was being affected by her developing illness .

"The Crown Princess needs more rest and her daily routine is changing faster than before," they say. "This means that changes to her official program may occur more frequently and at shorter notice than we are used to."