Officials are continuing to investigate how an undercover reporter with a British national newspaper breached security to enter the stabling area of leading grand national contender Hedgehunter.
A reporter from the Sun newspaper had his photograph taken with the horse, second favourite to win the famous steeplechase for a second successive year at Aintree later today.
Trainer Willie Mullins played down the incident, saying: "I think that if someone is determined to get into the stabling area then they will do. They appear to have done a good job in gaining entry.
"I have spoken to the girl who looks after Hedgehunter and she was with him the whole time. It is not unusual to be asked for a photograph, it's a regular thing."
The security breach is an embarrassment to the racecourse ahead of the world's biggest betting race in which bookmakers are predicting £250 million of bets on the four-and-a-half mile marathon, which starts at 3.15pm.
Aintree managing director Charles Barnett said responsibility for stable security lay with the horseracing regulatory authority (HRA).
HRA chief executive Peter Webbon said CCTV cameras had picked up the security breach. "This is the most photographed horse in Ireland, it's embarrassing in the sense that someone got unauthorised access to the yard, but the CCTV worked extremely well."
Hedgehunter romped to an easy victory last year but has to carry top weight of 11st 12lb this time. No horse has won back to back nationals or carried top weight to victory since Red Rum in 1974.
Clan Royal, second in 2004, is favourite to win a first national for champion jockey Tony McCoy.