The Duke of Edinburgh is likely to stay in hospital for observation and rest into next week, a source said.
Prince Philip was admitted to the King Edward VII Hospital in London on Tuesday, February 17, after feeling unwell.
A statement from Buckingham Palace originally said the Duke would remain in hospital for a few days but this has now been extended.
A royal source told PA: “Following consultation with his doctor the Duke of Edinburgh is likely to remain in hospital for observation and rest over the weekend and into next week.
“As we have said previously the doctor is acting with an abundance of caution. The Duke remains in good spirits.”