Prince Philip, the 96-year-old husband of Britain's Queen Elizabeth II, has been admitted to a London hospital, a royal spokesman said in a statement Tuesday.
The Duke of Edinburgh will undergo planned surgery on his hip at King Edward VII Hospital on Wednesday.
On Sunday, the Duke was absent from an Easter service attended by the Queen and other members of the royal family at St. George's Chapel in Windsor, also the venue for Prince Harry and Meghan Markle's wedding on May 19.
Last June, Prince Philip spent two nights in hospital as a "precautionary measure" for the treatment of an undisclosed infection.
In August 2017, the Duke retired from 65 years of public service, more than five years after the Palace originally said he would gradually "wind down" his workload, though he remained keen to carry out many of his duties.
Queen Elizabeth, 91, has also begun to scale back her duties due to her advancing age, handing over some of her responsibilities to her heir, Prince Charles.
The British monarch and her husband celebrated their 70th wedding anniversary last November.
The royal couple were married on November 20, 1947 when they were still Princess Elizabeth and Lieutenant Philip Mountbatten, at Westminster Abbey.
Prince Philip is the longest-serving consort in British history.