Prince Philip has been taken to hospital in London over a pre-existing condition, Buckingham Palace has said.
The prince is 98 years old and retired from public life in 2017 and has not been seen in public for a number of weeks.
He was taken into hospital as part of a "planned admission", the Palace added.
He was not taken to hospital by ambulance.
The palace said the Duke of Edinburgh is in hospital for "observation and treatment for a pre-existing condition".
The Duke is expected to be in hospital for a few days.
In a statement, the palace said Prince Philip travelled from Norfolk to the King Edward VI Hospital in London on Friday morning.
The palace said it was "on the advice of His Royal Highness's Doctor."
Since his retirement from solo Royal duties he has appeared in public alongside the Queen and other members of the Royal Family at events and church services.
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