Story highlights Prince Philip being treated for an infection arising from a pre-existing condition

Had announced his retirement from public life last month

London (CNN) Prince Philip, the 96-year-old husband of Britain's Queen Elizabeth II, was admitted to hospital Tuesday evening as a "precautionary measure," Buckingham Palace has told CNN.

The Prince, also known as the Duke of Edinburgh, was being treated at London's King Edward VII Hospital for an infection arising from a pre-existing condition.

"Prince Philip is in good spirits and is disappointed to be missing the State Opening of Parliament and Royal Ascot," Buckingham Palace said in a statement. The Queen, who will give her annual speech at the opening of Parliament today, will attend the Royal Ascot races later this afternoon.

Queen Elizabeth II and Prince Philip, Duke of Edinburgh, in their carriage during day one of Royal Ascot.

On Tuesday, before being admitted to hospital, the Prince donned a top hat for the first day of Royal Ascot in Berkshire, England.

The appearance was part of a scaled back schedule for the Prince, who announced last month that he would step down from public life

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