BRUSSELS (Reuters) - Belgium’s royal family has apologized to members of the public who were sent official cards that wrongly appeared to announce the death of King Philippe’s mother.

The palace said 150 people who sent letters of condolence on the death in December of Paola’s sister-in-law Queen Fabiola received replies thanking them for their “comforting words following the death of Her Majesty Queen Paola”.

“It’s a human error,” a spokesman told Reuters.

Paola, 77, is a blonde Italian princess who has long brought a dash of glamor to the Belgian royal house. She has played a less public role since her husband, King Albert II, abdicated in favor of their son Philippe in 2013.

Queen Fabiola, the Spanish widow of Albert’s late brother King Baudouin, died on Dec. 5 aged 86.