The Duke of Edinburgh, Prince Philip, has been admitted to hospital as a “precautionary measure”, Buckingham Palace has announced.
The 99-year-old was taken to King Edward VII hospital in London on Tuesday night.
A statement from Buckingham Palace said the prince was admitted on the advice of his doctor after feeling unwell.
He is expected to remain there “for a few days of observation and rest”.
It is understood the Duke was taken to hospital by car and walked into the hospital unaided, and his illness is not related to COVID-19.
He and the Queen have been staying at Windsor Castle, just outside of London, during the pandemic, and both received their COVID-19 vaccinations in early January.
Prince Philip was previously admitted to the same hospital just before Christmas in 2019 for treatment for a pre-existing condition, where he remained for several days.
The prince, who turns 100 in June, retired from public life in August 2017 but occasionally makes appearances at royal engagements.
In June last year Buckingham Palace released a photo of the Queen and the Duke at Windsor Castle to mark his 99th birthday.
He spent Christmas of 2011 in hospital after an operation to clear a blocked artery and he missed the end of celebrations to mark the Queen’s 60th year on the throne in 2012 after being hospitalised with a bladder infection.
In 2013, the Greek-born former naval officer underwent “an exploratory operation following abdominal investigations”.
He was admitted to hospital in 2017 for treatment for an infection, also arising from a pre-existing condition, and last year spent 10 days in hospital for hip-replacement surgery.
In January 2019, Prince Philip was unhurt when his Land Rover flipped after a collision with another car near Sandringham.
He gave up his driving licence after police gave him a warning for driving without wearing a seatbelt.