Prince Philip is receiving medical attention for an infection, Buckingham Palace confirmed.
"He is comfortable and responding to treatment but is not expected to leave hospital for several days," a palace spokesperson added.
The Duke of Edinburgh was taken to London’s King Edward VII Hospital last Tuesday evening after feeling unwell. His illness was not Covid-19 related.
The 99-year-old received a visit from his son the Prince of Wales in the weekend. Hospital Covid rules state a visit from one person can be considered "in exceptional circumstances".
The Queen remains at Windsor Castle.