The Duke of Edinburgh's condition has "improved considerably" though he is likely to remain in hospital over the next few days, Buckingham Palace said on Wednesday.
A spokesman added: "The treatment of his infection continues with antibiotics. He is likely to remain in hospital over the next few days. He is in good spirits."
Philip, 90, is suffering from a bladder infection and is being treated at King Edward VII Hospital in central London.
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Take a look at pictures from Tuesday's Diamond Jubilee celebrations below:
DIAMOND JUBILEE
- Thanksgiving Service At St Paul's Cathedral Begins With A Fanfare
- Kate Stuns In 'Nude' McQueen Dress
- Rowan Williams Praises The 'Huge Risk' Of Queen's Lifelong Dedication At St Paul's
- Gary Barlow, Cheryl Cole, Robbie Williams, Kylie Minogue, Paul McCartney Sing For Her Majesty (PHOTOS)
- HM Queen Moved By Duke Of Edinburgh's Absence, and Prince Of Wales's Emotional Tribute
- Kate, Duchess Of Cambridge, Stuns In 'Nude' Alexander McQueen Lace Dress
- Labour MP Lambasts Jubilee 'Slave Labour'