Prince Philip has been admitted to hospital on Tuesday for a few days "as a precautionary measure".
The 99-year-old royal – who is married to Britain's Queen Elizabeth II – is expected to spend a few nights at the King Edward VII hospital in London on the advice of his doctor after feeling unwell.
A statement from Buckingham Palace confirmed the Duke of Edinburgh's admission to hospital and said he would likely be there for a few days to rest and to be kept under observation.
It has not been confirmed why Prince Philip is currently in hospital at the time of writing. However, a palace source told the BBC that it was not related to coronavirus.
The Queen and Philip received their COVID-19 vaccinations last month.
The British monarch, 94, and her husband were administered the vaccine, reportedly by a doctor at Windsor Castle, as they are in the over 80s group, who are some of the first people to be vaccinated.
It is typically uncommon for the royals to issue statements on private health matters but it's believed the Queen decided to announce the news to avoid any speculation.