The Princess Royal's husband, Vice Admiral Sir Timothy Laurence, has tested positive for COVID-19, HELLO! understands.
The 66-year-old is believed to be isolating and following all the appropriate rules at the couple's Gatcombe Park estate in Gloucestershire.
It means that Princess Anne is therefore unlikely to visit her mother, the Queen, at Windsor Castle on Christmas Day.
WATCH: The royal family on Christmas Day at Sandringham through the years
It comes after the Queen cancelled her annual stay at her Sandringham estate for Christmas.
The monarch, 95, traditionally hosts her family in Norfolk over the holidays, and they are watched by crowds as they attend church on Christmas Day.
However, Her Majesty will spend the festive period at Windsor Castle for the second year running.
It's understood the decision was taken as a "precautionary" measure amid rising COVID-19 cases. A royal source has said the Queen will be visited by members of the royal family over the festive period, as she marks the first Christmas without her late husband, the Duke of Edinburgh, who passed away in April.
The royal source added sensible precautions will be taken by those visiting.
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© Photo: Getty ImagesThe couple have been married since 1992
It has not yet been confirmed where the Prince of Wales, the Duchess of Cornwall and the Duke and Duchess of Cambridge will be spending Christmas.
Last year, Prince Charles and Camilla stayed at their Gloucester home, Highgrove House, while the Cambridges spent Christmas at their Norfolk abode, Anmer Hall.
It seems likely that the Queen will be visited by her second son, the Duke of York, and his former wife, Sarah, Duchess of York, who live nearby at Royal Lodge.
Her Majesty's granddaughter, Princess Eugenie, is also currently living at the Duke and Duchess of Sussex's UK home Frogmore Cottage on the Windsor estate with her husband, Jack Brooksbank, and their ten-month-old son, August.
Last year the Queen and Prince Philip spent their first Christmas in Windsor in 33 years last year due to the pandemic.
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