The Duke of Edinburgh is spending a sixth day in hospital.
Philip, 91, was admitted to Aberdeen Royal Infirmary on Wednesday, during his and the Queen's annual summer break at Balmoral.
On Sunday, he missed a church service attended by the Royal family, as he continued to receive treatment for a flare-up of a bladder infection.
The Queen and the Prince of Wales were among those attending the service at Crathie Kirk, near Balmoral, while the Duke remained in hospital.
He has not received any visits from his relatives after being advised by doctors on Friday to rest, but is said to have been in regular contact by telephone.
When the Duke was admitted to the NHS hospital officials said that he would be in the infirmary for a few days, however, it remains unclear when he will be discharged.
His latest health scare comes less than three months after he spent five nights in hospital with a bladder infection following the Diamond Jubilee Pageant on the River Thames. He had to miss some of the key celebrations for the Queen's 60-year reign after he was admitted to the King Edward VII Hospital in London the day after braving wet and windy elements on a barge for several hours.
Philip also had a successful procedure to clear a blocked coronary artery in December and was in hospital for four nights over Christmas.
Philip went to Balmoral after attending several Olympic events. He was with the Queen during the opening ceremony and when they toured the Olympic Park. He then saw his granddaughter Zara Phillips' Olympic equestrian debut and watched boxing a few days later.
It is not yet known whether he will attend his next official engagement - accompanying the Queen to the opening of the London 2012 Paralympic Games on August 29.