The Princess of Wales is facing up to two weeks in hospital and several months' recuperation after undergoing successful abdominal surgery, Kensington Palace announced on Wednesday.
The 42-year-old wife of William, Prince of Wales, heir to the British throne, was admitted to a private clinic in central London on Tuesday, a statement said.
"The surgery was successful and it is expected that she will remain in hospital for ten to fourteen days, before returning home to continue her recovery," the palace added.
"Based on the current medical advice, she is unlikely to return to public duties until after Easter (on March 31)."
Royal officials refused to say what she was being treated for but confirmed the condition was non-cancerous.
The princess, widely known as Kate, is one of the most popular -- and photographed -- members of the royal family.
In the latest polling she was third most-popular living royal with a 63 percent public approval rating, behind William (68 percent) and King Charles III's sister Princess Anne (67 percent).
Queen Elizabeth II, who died in September 2022 aged 96, remains the most popular, with 75 percent, according to YouGov.
Catherine is frequently seen alongside William, 41, with whom she has three young children -- Prince George, 10, Princess Charlotte, eight, and Prince Louis, aged five.
But she is increasingly undertaking solo public engagements, particularly in her key areas of interest such as early years education.
Her last public engagement was on Christmas Day, when she joined her father-in-law the king, his second wife Queen Camilla, and other senior royals at a Christmas Day church service at Sandringham.
At The London Clinic, one of the UK's largest private hospitals, two police officers stood guard at the main entrance as photographers and film crews gathered.
Kensington Palace added: "The Princess of Wales appreciates the interest this statement will generate.
"She hopes that the public will understand her desire to maintain as much normality for her children as possible; and her wish that her personal medical information remains private.
"Kensington Palace will, therefore, only provide updates on Her Royal Highness' progress when there is significant new information to share.
"The Princess of Wales wishes to apologise to all those concerned for the fact that she has to postpone her upcoming engagements.
"She looks forward to reinstating as many as possible, as soon as possible."
The former Kate Middleton -- daughter of businessman Michael and ex-air stewardess Carole Middleton -- met William while they were both students at St Andrews University in Scotland.
The couple have been together ever since -- bar a brief breakup in 2007 that Kate has said made her "a stronger person".
She worked briefly as a buyer at high-street fashion chain Jigsaw before her marriage at London's Westminster Abbey in 2011, where she wore a lace-sleeved gown by Alexander McQueen's Sarah Burton.
William's choice to marry a so-called "commoner" after a live-in relationship sharply contrasted with his father in his first marriage in 1981 to 20-year-old aristocrat Diana Spencer, 12 years his junior.
Kate has since given little away about her experiences in joining the royal family, unlike her sister-in-law Meghan, who married William's younger brother, Prince Harry, in 2018.
Harry and Meghan sensationally quit frontline royal duties and moved to North America in March 2020, from where they have repeatedly criticised life behind the palace walls.
