Irish amateur jockey Rob James says he is "heartbroken" and wishes to apologise after a video of him climbing on a dead horse appeared on social media.
James told the Irish Field newspaper he was the person in the video which circulated on social media earlier in the day.
It shows him briefly climbing on the dead horse while others present could be heard laughing. James said the mare died following a cardiac arrest on a gallops in April 2016.
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His apology came after Irish trainer Gordon Elliott on Monday was temporarily banned from racing in Britain when a photograph of him sitting on a dead horse circulated online.
Elliott, a Gold Cup and three times Grand National winner, said the photograph was taken some time ago after a horse had died of an apparent heart attack on the gallops.
He apologised for "any offence caused".
James, who rode Elliott-trained Milan Native to victory at the Cheltenham Festival last year, also said he was sorry.
"I would just like to apologise for my actions which were wholly inappropriate and disrespectful," James told the Irish Field newspaper.
"I sincerely apologise to the owners of the mare, the staff who cared for her, the horseracing industry, and all followers of horse racing for my actions."
The Irish Horseracing Regulatory Board (IHRB) had earlier said on Twitter that it was "aware of further social media content circulating" and the matter was under investigation.
"To try defending my stupidity at the time would add further insult and hurt to the many loyal people that have supported me during my career," James said.
"I am heartbroken by the damage I have caused and will do my best to try and make amends to those hurt by my conduct."
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