The British authorities said on Wednesday that they were investigating after a report that an employee had tried to obtain the private medical records of Catherine, Princess of Wales, at the London hospital where she underwent abdominal surgery in January.

The hospital, the London Clinic, a private institution with an elite clientele, has opened an investigation of the alleged breach, according to The Daily Mirror, a British tabloid, which first reported the matter on Tuesday evening.

A spokesman for the Information Commissioner’s Office, which oversees data protection issues in Britain, said on Wednesday, “We can confirm that we have received a breach report and are assessing the information provided.”

The Mirror said that the hospital had reported the incident to Kensington Palace, where Catherine and her husband, Prince William, have their offices. “This is a matter for the London Clinic,” a spokesman for the palace said.

It is unclear whether the employee succeeded in gaining access to the files or in sharing them with anyone outside the hospital. But the allegations added another layer of intrigue to Catherine’s sudden hospitalization and prolonged recovery, which has already become the source of feverish rumors and conspiracy theories.

For all the speculation, there has been no informed reporting about the condition that prompted Catherine’s surgery. The palace has disclosed almost no details, saying in its initial statement that it was Catherine’s “wish that her personal medical information remains private.”

In recent weeks, as Catherine has stayed out of the public eye, social media users have conjured up increasingly wild theories about her prognosis, her whereabouts and even her relationship with her husband.

Catherine, 42, contributed to the maelstrom by admitting last week that she had digitally altered a Mother’s Day photograph of her with her three children. The palace released the picture, which it said had been taken by William a few days earlier, in a misbegotten effort to dampen the public speculation.

On Monday, the news agency Getty Images added an advisory to a second, earlier photograph, taken by Catherine of Queen Elizabeth II surrounded by the monarch’s grandchildren and great-grandchildren. The agency said that picture showed signs of being “digitally enhanced.”

On Monday, two London tabloids published images and a video which appeared to show Catherine and William walking out of a food shop near their home in Windsor, west of London, this past weekend. If authenticated, it would be the first footage of Catherine to reach the public since before she entered the hospital in January.

Kensington Palace declined to comment on the video, sticking to its policy that it would offer no information about Catherine’s recovery beyond saying that she would return to official duties sometime after the Easter holiday.

The allegation that a staff member may have attempted to breach Catherine’s private medical records is an embarrassment for the London Clinic, which has treated other members of the royal family, as well as celebrities such as the actress Elizabeth Taylor and foreign leaders including the Chilean dictator Gen. Augusto Pinochet. John F. Kennedy was told by doctors he had Addison’s disease while a patient at the hospital in 1947.

Catherine spent nearly two weeks at the hospital, during which she was visited by King Charles III, who checked in himself around the same time for treatment of an enlarged prostate. After he was released, Buckingham Palace disclosed that doctors had found an undisclosed form of cancer during his procedure.

The palace zealously protected Catherine’s privacy during her stay. There were no pictures of her children going to visit her at the hospital, which is in the Marylebone neighborhood of London, and only a single shot of William, at the wheel of a car outside, presumably after a visit.

On the day she was released, the palace said, “the Prince and Princess wish to say a huge thank you to the entire team at the London Clinic, especially the dedicated nursing staff, for the care they have provided.”