She was covered a month ago by last year's unbeaten Derby and Arc de Triomphe hero Lammtarra and tested positive in foal only the day before her death.
Bell said yesterday: "She was a great racehorse, our first Group One winner and a pleasure to train in every way. She was retired six weeks ago and was covered by Lammtarra two weeks later. Her first test proved positive. She looked marvellous when I last saw her but unfortunately she contracted a colic-related illness which sadly proved fatal."
Hoh Magic gained her Group One success in the 1994 Prix Morny at Deauville. The chestnut filly received a rating of 117 in that year's International Classifications - 13lb behind the top-rated Celtic Swing.
Simon Weinstock, obituary, page 12