Royal Editor Chris Ship reports from outside King Edward VII's hospital
The Duke of Edinburgh is to stay in hospital for several days in order to receive treatment for an infection.
Buckingham Palace said Prince Philip is "comfortable and responding to treatment."
The statement from Buckingham Palace said: "The Duke of Edinburgh remains at King Edward VII's Hospital where he is receiving medical attention for an infection."He is comfortable and responding to treatment but is not expected to leave hospital for several days."
His son Prince Edward told Sky News the Royal Family were keeping "their fingers crossed" but added the Duke was recovering.
The Earl of Wessex said: "As far as I'm aware, well I did speak to them the other day, so he's a lot better thank you very much indeed, and he's looking forward to getting out, which is the most positive thing."
Asked whether Philip was frustrated to be in hospital, Edward laughed and replied: “Just a bit. I think that gets to all of us, and then you can only watch the clock so many times and the walls are only so interesting.
“We’ve had some brilliant and lovely messages from all sorts of people and we really appreciate that and so does he, I’ve been passing them on. It’s fantastic, thank you.”
ITV Royal Editor Chris Ship said the latest statement suggests the infection "is more serious than first thought".
Statements from the Palace last week emphasised the Duke was only in hospital out of "an abundance of caution" after he reported feeling unwell.
The Duke, 99, was visited by Prince Charles on Saturday after making a 200 mile round trip from his home in Gloucestershire.