Racehorse trainer Gordon Elliott has been roundly criticised after a photograph circulated on social media showed him sitting on a dead horse.
Elliot, a three-time Grand National winner, had earlier confirmed the image - which shows him sitting on the horse while making a phone call and a gesture towards the camera with two fingers held up - was genuine and apologised for "any offence caused".
The British Horseracing Authority (BHA) said it was appalled while Horse Racing Ireland condemned the "disturbing" image unreservedly.
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"We expect all those in our sport to demonstrate respect for horses, on the racecourse, in the training yard, on the gallops, and wherever they have horses in their care," said the BHA statement.
"People who work in our industry believe their values -- of caring for and respecting our horses -- have been deeply undermined by this behaviour," it added.
"On their behalf, and on behalf of all horse-lovers, we say unequivocally that British horseracing finds this totally unacceptable."
The BHA said it was considering its own regulatory options. The image showed Elliott sitting on a dead horse at a training yard while making a phone call.
The trainer said he was "co-operating fully" with the Irish Horseracing Regulatory Board (IHRB) which has launched an investigation.
Horse Racing Ireland, the national authority for thoroughbred racing, said the image "does a disservice to the thousands of people who look after their horses on a daily basis".
Elliot said in a statement that the photo had been taken some time ago after a horse had died of an apparent heart attack on the gallops.
"At what was a sad time... my initial reaction was to get the body removed from where it was positioned," he explained.
While standing over the horse, he said he received a phone call and, "without thinking", sat down to take it.
"Hearing a shout from one of my team, I gestured to wait until I was finished...Such background information may seem trivial at this time...However, I feel it is important to provide people with some context surrounding this photo."
Eight-time champion jump jockey Peter Scudamore called the photo "an act of crass stupidity".
"It just hit the bottom of my stomach," said the 62-year-old is quoted as saying by the BBC.
"I think everybody in racing I know hoped it was fake, and then there was a slow realisation that it's not a fake. It's desperate sadness on so many fronts. It is just such an appalling image and I'm very sad about it."
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