Two Australian radio DJs made a prank call to the hospital where Prince William's pregnant wife, Catherine, is staying with acute morning sickness, claiming to be Queen Elizabeth II and her son, Prince Charles.
The DJs, from Sydney's 2Day FM station, succeeded in getting through to Kate's private nurse at King Edward VII Hospital and had a brief conversation that included some details of her condition, according to audio of the call posted online.
The hospital issued a statement Wednesday confirming that the hoax call had been transferred to a ward in the early hours of Tuesday morning and a short conversation was held with one of the nursing staff.
The hospital "deeply regrets" the incident, it said.
John Lofthouse, chief executive at the hospital, is quoted as saying: "This was a foolish prank call that we all deplore. We take patient confidentiality extremely seriously and we are now reviewing our telephone protocols."
Prince William's office at Clarence House has not commented on the incident.
The radio show posted an apology for the call on its official Twitter feed Wednesday, and issued a statement.
"2Day FM sincerely apologises for any inconvenience caused by the enquiry to Kate's hospital, the radio segment was done with light-hearted intentions, we wish Kate and her family all the best and we're glad to hear she's doing well," it said.
The two DJs, Mel Greig and Michael Christian, are quoted as saying: "We were very surprised that our call was put through, we thought we'd be hung up on as soon as they heard our terrible accents."
An earlier tweet by 2Day FM had described it as a "hilarious prank."
Catherine, the Duchess of Cambridge, is still receiving treatment after she was admitted to the hospital Monday with hyperemesis gravidarum, a condition which involves nausea and vomiting more severe than the typical morning sickness many women suffer during early pregnancy
Audio of the call posted online reveals that the nurse, sounding nervous, divulged general details of Kate's condition and care.
She also tells DJs, who host the Summer 30 show on 2Day FM, what time William left the previous evening and suggests they visit after 9 a.m. that day.
The incident is bound to raise concerns over security and privacy provisions at the hospital.
Greig, who impersonated the queen, exclaims after the call ends: "She was giving us real information!"
The conversation was conducted in poorly done English accents and with frequent references to "Charles" walking the queen's corgis, her much-loved dogs, but it did not appear to raise alarm bells with hospital staff.
The DJs commented on how easy it was to make the prank call.
The queen was previously the object of a prank call in 1995, when Canadian DJ Pierre Brassard got through to Buckingham Palace pretending to be then-Canadian Prime Minister Jean Chretien.
According to UK media reports at the time, they spoke for about quarter of an hour and discussed an upcoming referendum on independence for Quebec.
The palace said Monday that Catherine, 30, is likely to remain in the hospital for several days.
The duchess is not yet 12 weeks pregnant, Clarence House told CNN, so the palace is not announcing a due date for the child.
William and Catherine's child will be next in line to the British throne after William, regardless of whether it is a boy or a girl.
Planned changes to the law of succession that end the tradition of a boy jumping over an elder sister are already de facto in effect, the British Cabinet Office said.
Deputy Prime Minister Nick Clegg said Tuesday that all 16 countries that recognize the British monarch as their head of state have formally agreed to the change and British lawmakers will change the rules as soon as possible.
Clegg also said that the change in succession will allow someone in line to the throne to marry a Catholic -- but not to be a Catholic. The Church of England is the nation's official church. It split from the Roman Catholic Church in the 16th century.