The Equestrian Federation of Ireland has said a case file regarding the horse ABC Landliebe was amongst the items stolen during a burglary at the federation's offices at Kill, Co Kildare, yesterday.
ABC Landliebe was ridden by the showjumper Cian O'Connor.
In a statement, the EFI said the file on the horse Waterford Crystal was not stolen, and is now in the custody of the gardaí.
The statement is the first confirmation that the burglary was linked to the doping controversy surrounding the Olympic showjumping gold medallist, Cian O'Connor.
The theft follows Monday's revelation that a urine sample from Mr O'Connor's horse, Waterford Crystal, had been stolen while en route to a laboratory in England last month.
Earlier, the EFI said it was seeking clarification as to why the so-called 'B' sample, taken from Waterford Crystal, is being re-routed to laboratories in New York.
Initially the sample was to be tested in England but it was announced this morning that it would be analysed at the Hong Kong Racing Laboratory.
The International Equestrian Federation's legal team informed Mr O'Connor's solicitor of the change of plan last night.
