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.
Mel Greig and Michael Christian from Sydney's 2Day FM were transferred to a duty nurse who divulged details of how doctors were treating the duchess.
The hospital has said it "deplores" the stunt and will be conducting a review of its phone system.
As Prince William arrived to visit his wife as she spends her third day in hospital, St James's Palace declined to comment on the incident.
He left just after 5pm after spending five hours with his wife.
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."
Michael Christian has been posting congratulatory Tweets and reports of the prank from around the world on his Twitter page.
He tweeted: "Can't believe we got put through!"
The DJs and their radio station have since apologised - saying the hosts had "the best intentions".
Mel Greig and Michael Christian said: "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.
"We're very sorry if we've caused any issues and we're glad to hear that Kate is doing well."
In a statement, 2Day FM said: "2Day FM sincerely apologises for any inconvenience caused by the inquiry to Kate's hospital, the radio segment was done with the best intentions and we wish Kate and her family all the best."
Earlier today Kate's sister Pippa and her brother James spent an hour visiting her in the hospital.
The Duchess' parents Carole and Michael Middleton are thought to have visited their daughter on Tuesday.
Knowingly or recklessly obtaining personal information without consent is an offence under Section 55 of Data Protection Act 1998, punishable by a fine of up to £5,000.
During the debate over UK press standards, Deputy Prime Minister Nick Clegg called for those guilty of obtaining personal information by deception - known as "blaggers" - to be jailed.