The BBC has apologised after a dummy tweet claiming the Queen was being "treated" in hospital was posted on the internet by mistake.
The tweet was part of a technical rehearsal for the broadcaster's future coverage of the Queen's obituary.
By coincidence, the Queen was at hospital earlier today for her routine annual medical check-up.
Buckingham Palace took the unusual step of confirming the private medical visit following mounting speculation on social media about the state of her health following the tweet.
The message was posted on Twitter from the account of BBC broadcast journalist Ahmen Khawaja.
It said: "Breaking: Queen Elizabeth is being treated at King Edward VII Hospital in London. Statement due shortly."
The journalist later deleted the tweet, apologised for what she described as a "false alarm" and suggested her phone might have been hacked.
Ms Khawaja tweeted: "Phone left unattended at home. Silly prank. Apologies for upsetting anyone!"
After speculation began to mount about the Queen, a Buckingham Palace spokesman said: ''I can confirm that the Queen this morning attended her annual medical check-up at the King Edward VII's Hospital in London.
''This was a routine, pre-scheduled appointment, the Queen has now left hospital.''
The BBC apologised for the tweet which it said was part of an exercise and had been posted in error.
It said in a statement: "During a technical rehearsal for an obituary, tweets were mistakenly sent from the account of a BBC journalist saying that a member of the Royal Family had been taken ill. The tweets were swiftly deleted and we apologise for any offence."