Ireland will follow up on any breaches in legislation regarding the slaughter of horses, according Agriculture Minister Charlie McConalogue.
He was speaking after a BBC Panorama documentary found successful racehorses, linked to some of the biggest names in racing, were among thousands slaughtered in British and Irish abattoirs since 2019.
Footage filmed inside one of the UK's biggest abattoirs claimed that rules designed to protect horses from a cruel death were being breached.
The BBC says Freedom of Information requests revealed that 4,000 former racehorses were slaughtered in Ireland and Britain since the beginning of 2019.
Most - but not all - were trained in Ireland, it says.
The footage was recorded over four days at the end of 2019 and the start of 2020.
Horse Racing Ireland says it unreservedly condemns the practices, and supports calls for an investigation by the relevant UK authority.
Minister McConalogue told Newstalk Breakfast it is completely unacceptable.
"Absolutely unacceptable in any situation where a horse would be travelling like that from the Republic to Britain - in fact it would be illegal and would be followed up rigorously by the department.
"There is a process in place within Ireland where there's one processor in the country actually authorised for processing horse meat for human consumption.
"We've about 5,000 or 6,000 horses a year - which would be with very tight regulation, oversight and welfare oversight - actually processed in that manner."
Minister McConalogue says there is an agreement for free travel of horses between Ireland and the UK, but this does not cover the purpose of going to an abattoir.
"Any such behavior is absolutely illegal, because we take horse welfare very, very seriously and there's very strict regulation in relation to that.
"And any incident will be followed up to the letter of the law, and also breaches - where we become aware of it - will be followed up very, very strictly and with great authority as well".