Prince William said Prince Philip is "ok" and doctors are "keeping an eye on him" in hospital.

The Duke of Cambridge made the comments during a visit to a vaccination centre in King's Lynn, Norfolk.

At the end of his tour of the inoculation hub, set up in the King’s Lynn Corn Exchange, the duke was quizzed about the Duke of Edinburgh and replied: “Yes, he’s OK, they’re keeping an eye on him,” and gave a wink.

Philip, 99, is now into his seventh day at the private King Edward VII’s hospital in central London.

He was admitted on Tuesday evening as a precautionary measure after feeling unwell and walked into the building unaided.

He was initially due to spend a few days under medical care for “observation and rest” for the undisclosed reason.

But on Friday sources said the duke was likely to remain in hospital into this week.

He received a visit from the Prince of Wales on Saturday – a rare occurrence as the duke is known for his “no fuss” attitude.

A royal source said the reason for the hospital stay was not coronavirus-related.

Both the Duke and the Queen had their COVID-19 vaccines in January.

News Shopper: Police officers stand at the entrance to the King Edward VII Hospital in London where the Duke of Edinburgh was admittedPolice officers stand at the entrance to the King Edward VII Hospital in London where the Duke of Edinburgh was admitted

On Saturday, Charles and Philip spent about 30 minutes together.

Charles travelled from Highgrove in Gloucestershire and was visiting because the duke had been in hospital a little longer than expected.

On Friday, it was reported that the Duke of Edinburgh was likely to remain in hospital until later this week for rest and observation, although he was said to be in "good spirits".

There were no further visits to the Duke by family members on Sunday, though police and security cars remained in place at the hospital throughout the day

Heart-shaped balloons and a letter written by a 10-year-old boy from north London, wishing Prince Philip a quick recovery, were tied to the hospital railings.

He has been staying with the Queen at Windsor Castle since coronavirus restrictions were first introduced last year.

The Prince will turn 100 on 10 June.