Phillips - here on Ardfield Magic Star - fell on Tsunami II last year
Zara Phillips has broken her collarbone at a cross country event in France.
The reigning eventing world champion and Queen's granddaughter fell from her horse Tsunami II in Pau.
The 11-year-old horse tripped at the 15th fence, throwing off Phillips and breaking its neck. It was later put down, leaving Phillips "devastated".
Phillips, who fell at the Burghley Horse Trials last month, is expected to take three months to recover and will be out for the rest of the season.
Phillips had been riding the 11-year-old mare for four years and also fell while riding her at the Braham International Horse Trials in Yorkshire last year and at a World Cup qualifier in Ireland in June.