The Irish government has pledged to probe suspected malpractice at a horse abattoir after a television investigation raised food safety concerns.
A documentary by public broadcaster RTE aired recently included covert footage of staff members at the facility inserting false identification microchips into horses and using spray paint to change the colour markings on horses.
Agriculture minister Charlie McConalogue said the scenes were "abhorrent and unacceptable".
"No stone will be left unturned in terms of making sure the full rigours of the law are applied here," McConalogue told RTE radio.
The RTE documentary also examined criminal networks across Europe engaged in "disappearing" horses by laundering identities of animals declared unfit for human consumption, to get them into the human food chain.
Horses not supposed to be going into the food chain were doing so by receiving "a new passport", veterinary expert David Martin told the broadcaster.
The practice was "putting human safety at risk" and "compromising the food chain", he added.
In recent weeks the agriculture ministry and police conducted searches at the facility, Ireland's only horse abattoir, in Straffan, west of Dublin, examining the supply of horses for slaughter.
"All available evidence of illegal activity... will be appropriately investigated," said a ministry statement.
"Horses are primarily bred for recreation as opposed to the food chain and we have very strict laws in place as well in relation to the management of that food chain," said McConalogue.
Traceability of some 20,000 Irish horses each year could be affected by the malpractice, said the television report.
According to data analysed by RTE on thousands of horses sent for slaughter since 2023 most were thoroughbreds for the racing industry, with the rest bred as sport or leisure horses.
More than 400 of those bred for racing had racing careers, with some arriving at the abattoir from prestigious owners and trainers, and killed just days after their last race, said the broadcaster.
Horse Racing Ireland (HRI), the sport's governing body, has said it will actively support any government or police investigation.
HRI said in a statement that it was "deeply shocked and appalled" by the content of the documentary.
The abattoir operator Shannonside Foods said in a statement that it rejects the claims.
