The Duke of Edinburgh is expected to remain in hospital for "observation and rest" into next week, sources have said.
Philip was admitted to King Edward VII's hospital on Tuesday evening after feeling unwell and walked unaided into the medical centre.
The Duke, who turns 100 on June 10, is in hospital for an undisclosed reason, although it is not coronavirus-related.
Sources told PA news agency: "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."
