By Sean Seddon, BBC News
The Princess of Wales, pictured in November 2023. Photo: AFP / FRANK AUGSTEIN
The data watchdog is assessing a report staff at the hospital where the Princess of Wales had surgery tried to view her private health information.
The Daily Mirror claimed staff at the London Clinic - which is frequently used by royals - "attempted to access her private medical reports".
The Information Commissioners' Office (ICO) confirmed it received a "breach report" and is making inquiries.
BBC News has contacted the London Clinic for comment.
According to the Mirror, "at least one member of staff was said to have been caught trying to access" the princess's medical notes.
The paper said an internal investigation has been launched at the private London hospital, which has treated both the Princess of Wales and King Charles III in recent months.
Catherine underwent abdominal surgery for an undisclosed condition in January and has stepped back from public duties while she recovers.
Asked about the Mirror report, an ICO spokesperson said: "We can confirm that we have received a breach report and are assessing the information provided."
BBC News has not been able to independently verify the Mirror's claims, which were published late on Tuesday (local time).
A Kensington Palace spokesperson declined to confirm or deny the report, adding: "This is a matter for The London Clinic."
The allegations come after a flurry of online speculation and conspiracy theories about the Princess of Wales's health during her absence from public-facing engagements.
Catherine also apologised after it emerged a Mother's Day photo of her and her three children had been edited, an incident which further fuelled rumours on social media.
The princess spent almost two weeks at the London Clinic and Kensington Palace previously said she would recuperate until after Easter.
On Monday, the Sun published a photograph of William and Catherine shopping in Windsor, their first public outing since Christmas.
This story was originally published by the BBC.