Prince Philip has "reluctantly decided" on "doctor's advice" not to attend today's events marking the Battle of Jutland centenary, Buckingham Palace has said.
The Duke of Edinburgh's ailment has been described as "minor" and he is not planning to cancel any other engagements this week.
"The background is that this is on the doctor's order, but there are no plans for him to go to hospital," a spokesperson for Buckingham Palace told The Independent. "This is a temporary health thing."
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The 94-year-old Duke has had health problems in the past that have caused him to pull out of public engagements. He was hospitalised twice with a recurring bladder infection in 2012, following the Diamond Jubilee Pageant on the River Thames, and had surgery to clear a blocked artery the previous year.
He had been due to attend a service at St Magnus Cathedral in Kirkwall, Orkney, today, followed by a commemorative event at Lyness Royal Naval Cemetery on Hoy.
The Princess Royal, who was already scheduled to attend, will represent the royal family at the events. Her husband, Vice Admiral Sir Tim Laurence, told Sky News: "[The Duke] is very frustrated and disappointed that he can't be here and we're all very sad that he won't be with us.
"He's fine. He just has a minor ailment and I think at his age, it would be unwise to go and stand in a windswept cemetery for a long period."
The Duke has written a message on the Order of Service for the centenary commemorations, in which he says the events were focused on the "endurance and gallantry" of all those who took part.
Philip's father-in-law, King George VI, fought at Jutland aboard HMS Collingwood while still Prince Albert.