The Duke of Edinburgh has been taken to hospital in Aberdeen.
Buckingham Palace confirmed the Duke had been taken to Aberdeen Royal Infirmary on Wednesday afternoon.
The Palace said it was a "precautionary measure", adding later that the Duke had been diagnosed with a recurrence of a bladder infection that first occurred earlier this year during the Queen's jubilee.
Prince Phillip had been staying at the Royal family’s Scottish retreat at the Balmoral Estate with the Queen.
A spokesman said Philip travelled to the hospital, about 40 miles away from Balmoral, by road and that medical assessments would be carried out if needed.
The spokesman added: "He has been resident at the castle for a short while but whilst he has been there, he has also undertaken engagements on the Isle of Wight."
Philip was at the Queen's side during the Opening Ceremony of the London Olympics on July 27 and the following when they toured the Olympic Park.
While in Scotland earlier this month he supported the Queen at engagements including hosting a tea party at Balmoral to mark the end of her Diamond Jubilee celebrations and attended at Crathie Church close to the Royal estate with the Queen on Sunday.
Philip joined the Queen and the Earl and Countess of Wessex at the event on the estate which was attended by around 3000 guests.
The royals, including the Duke, reportedly looked relaxed during the event, which rounded off the Queen's Diamond Jubilee celebrations.
Aboyne, Upper Deeside and Donside councillor Peter Argyle said: “I was privileged to be at the garden party at Balmoral last week and saw the Duke of Edinburgh there and I know he is held in the highest esteem and with the greatest respect on Deeside and I’m sure everyone will wish him well.
“I was very, very fortunate to speak to the Queen and was fairly close to him and he looked his usual self. Of course he’s not a young man anymore and has had a few health scares already but he wasn’t showing any signs of slowing down.
“He was talking to everybody. From when they came out of the castle until the time they got to their tea. Both of them must have been on their feet and talking to people for at least an hour.”
Earlier this year the 91-year-old was as taken to the King Edward VII Hospital in London from Windsor Castle as a precautionary measure during the Diamond Jubilee celebrations with a bladder infection.
Last December he underwent a successful procedure to clear a blocked coronary artery and was in hospital for four nights over Christmas.
Before the heart scare he had been fit and apparently healthy, and led the active life of a man of younger years.
In March this year his grandson Prince Harry said the operation had given him "a new spurt of life".
On Wednesday night Dr Malcolm VandenBurg, a Harley Street specialist in general medicine and male health problems, said there could be numerous causes for the recurrence.
The consultant said there were three more likely causes: an enlargement of the prostate gland, cancer in the prostate or an infection in the actual prostate.
The doctor said the Duke of Edinburgh’s "exceptional medical team" would also be studying if there was something else making the body prone to infection, such as diabetes.
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