Prank callers have managed to trick hospital staff treating the Duchess of Cambridge into revealing detailed information about her condition.
Australian radio DJs impersonating the Queen and Prince of Wales were given an update about Kate, who was admitted to London's King Edward VII on Monday with severe morning sickness.
The 2Day FM presenters were put through to a nurse who reportedly told them: "She's sleeping at the moment and she has had an uneventful night. She's been given some fluids, she's stable at the moment."
The hospital has denounced the prank call as "foolish" but St James's Palace has declined to comment.
A spokesman for the hospital said: "King Edward VII's Hospital Sister Agnes can confirm that an Australian radio station made a hoax call to the hospital in the early hours of Tuesday morning.
"This call was transferred through to a ward and a short conversation was held with one of the nursing staff. King Edward VII's Hospital deeply regrets this incident."
John Lofthouse, chief executive at King Edward VII's Hospital, said: "This was a foolish prank call that we all deplore. We take patient confidentiality extremely seriously and we are now reviewing our telephone protocols."
The radio presenters, Mel Greig and Michael Christian, were told by the nurse that they could visit the Duchess after 9am.
She told the hoax Queen and Charles: "I would suggest that any time after nine o'clock will be suitable to visit. We'll be getting her freshened up."
The nurse added: "She's quite stable. She hasn't had any retching with me and she's been sleeping on and off."
The prank call will be deeply embarrassing for the Edward VII Hospital, which is the medical institution of choice for the Royal Family.
The Queen, Duke of Edinburgh and Duchess of Cornwall have all been treated at the institution over the years.
William is likely to be angered by the intrusion into his wife's health, despite the call having a humorous rather than sinister motive.
The royals have been the target of hoax callers before.
In 1995 Canadian DJ Pierre Brassard, pretending to be Canadian Prime Minister Jean Chretien, was put through to the Queen.
The pair spoke for around 15 minutes and he even managed to elicit a promise that she would try to influence Quebec's referendum on proposals to break away from Canada.