The Duke of Edinburgh faces a fourth day in hospital as he recuperates following exploratory abdominal surgery.
Philip, who is 92 tomorrow, was admitted to the London Clinic on Thursday following a garden party at Buckingham Palace and underwent the procedure on Friday.
The original symptoms that prompted the operation have not been released by Buckingham Palace, but it is thought the procedure did not involve his heart or bladder, organs the Duke has experienced problems with before.
Analysis of the results of the operation are expected to be completed next week.
He was visited by royal doctor Professor John Cunningham yesterday morning, according to reports - though the palace would not confirm his attendance.
Royal officials said they did not anticipate releasing any further updates over the weekend regarding the Duke's health, after saying on Friday he was "progressing satisfactorily".