Nine horses from John Magnier's Coolmore Stud have been detained, including former champion Rock of Gibraltar . . . the horse at the centre of a major ownership dispute between Magnier and Alex Ferguson in 2003. Also in quarantine is one of Coolmore's most expensive sires, Danehill Dancer, which can earn up to 280,000 per day.

Five stallions from Kildangan Stud in Co Kildare are also being held, as well as one privately-owned horse from the Irish National Stud. The Irish stallions, in Australia for the start of the breeding season, are among 79 horses from around the world to be put in quarantine.

Early estimates have predicted the emergence of the disease could cost the racing industry as much as 60m.

However, a Coolmore spokesperson yesterday told the Sunday Tribune the 30-day quarantine period meant the horses would miss just the first three weeks of the breeding period.

"At this point, a three-week delay is manageable for our business, " said the spokesperson. "We will be working with clients to minimise any disruption to the business."

Australian officials are currently investigating the source of the virus, which is believed to have been brought in by stallions from Japan.

Horses in the two quarantine centres are being tested for the disease and the government yesterday put a 72-hour ban on all horseracing across the country.