Prince Philip has spent a second night in hospital after becoming unwell earlier this week.
The Duke of Edinburgh, 99, was admitted to the King Edward VII Hospital in central London on the evening of Tuesday 16 February, as a precaution after falling ill.
The Duke is said to be in “good spirits” and is expected to remain at the hospital for a few days for both observation and rest.
It is understood that the duke had been feeling unwell for a short period before the doctor was called. He was not an emergency admission and travelled to the hospital by car.
A palace source has said he walked into the palace unaided and his condition is not related to Covid-19. The Queen has remained at Windsor Castle and continues to work as normal.
Prince Philip and the Queen have both been spending the recent lockdown in Windsor Castle with a small number of household staff.
The couple received coronavirus vaccines from a household doctor at Windsor Castle in January.
‘The duke’s admission is a precautionary measure’
Prince Philip’s admission to hospital is said to be on a precautionary basis, based on the advice of his doctor.
Buckingham Palace said in a statement: “His Royal Highness the Duke of Edinburgh was admitted to King Edward VII’s Hospital in London on Tuesday evening.
“The duke’s admission is a precautionary measure, on the advice of His Royal Highness’s doctor, after feeling unwell.
“The duke is expected to remain in hospital for a few days of observation and rest.”
A spokesman for Prime Minister Boris Johnson said: “The PM sends his best wishes to the Duke of Edinburgh as he undergoes a few days of rest in hospital.”