A security breach has reportedly taken place at the private London hospital where the Princess of Wales underwent abdominal surgery in January.
An investigation has been launched at the London Clinic after it was claimed that at least one member of staff had tried to access Kate's private medical records.
A hospital insider has told The Mirror: "This is a major security breach and incredibly damaging for the hospital, given its unblemished reputation for treating members of the Royal Family.
"Senior hospital bosses contacted Kensington Palace immediately after the incident was brought to their attention and assured the palace there would be a full investigation.
"The whole medical staff have been left utterly shocked and distraught over the allegations and were very hurt that a trusted colleague could have allegedly been responsible for such a breach of trust and ethics."
In response, a Kensington Palace spokesperson said: "This is a matter for The London Clinic."
The London Clinic’s chief executive, Al Russell, said in a statement on Wednesday: "Everyone at the London Clinic is acutely aware of our individual, professional, ethical and legal duties with regards to patient confidentiality. We take enormous pride in the outstanding care and discretion we aim to deliver for all our patients that put their trust in us every day.
"We have systems in place to monitor management of patient information and, in the case of any breach, all appropriate investigatory, regulatory and disciplinary steps will be taken. There is no place at our hospital for those who intentionally breach the trust of any of our patients or colleagues."
Kate spent 13 days in the private hospital following her surgery on 16 January. Details of the Princess' condition have not been revealed but Kensington Palace previously said it was not cancer-related and that Kate wished her personal medical information to remain private.
King Charles was also treated for an enlarged prostate at the same hospital as his daughter-in-law, with the pair both being discharged on 29 January.
The London Clinic was officially opened by the then-Duke and Duchess of York in 1932. It was the brainchild of a group of Harley Street doctors who set out to plan a new nursing home using the highest medical standards of the day.
Past high-profile patients include the late Duke of Edinburgh, the late Queen's younger sister Princess Margaret, former US president John F Kennedy and actress Elizabeth Taylor.
News of the hospital security breach comes the day after footage of the Prince and Princess of Wales leaving the Windsor Farm Shop near to their home, Adelaide Cottage, was shared by The Sun and TMZ.
In the clip, Kate, wearing an Umbro hoodie and sports leggings, was seen chatting with her husband, Prince William, and carrying a large white bag as the pair left the store.
The Princess has only been photographed twice since her surgery, including on the way to a private appointment in London as William travelled to the Commonwealth Day service at Westminster Abbey.
Online speculation and conspiracy theories about Kate heightened after news agencies pulled the Mother's Day photograph of the Princess and her children after it was found to have been digitally altered, with the royal later admitting to “editing” the image and apologising for any “confusion” caused.
The Princess is not expected to return to royal duties until after Easter.