A Co Monaghan beef processing company has said there was "clearly an issue" with their Polish supplier after a consignment was found to contain 80% horse meat.
Martin McAdam of McAdam Food said he was working with the Department of Agriculture and the Food Standards Agency (FSA) and had provided them with documentation.
In a statement the company said it had no awareness or knowledge of any possibility of equine content in meat products imported and supplied by it to any other company.
It said: "McAdam Foods states and confirms that any such products were bought and imported on the basis of their being ordered, documented, labelled and understood to be beef, and nothing else.
"The company has supplied all such labels and documentation to inspectors of the Department of Agriculture and the FSAI".
Earlier, Freeza Meats in Newry, where the consignment was stored, said Mr McAdam had asked them to purchase a parcel of raw material, which they declined.
The company was asked by Mr McAdam to hold his product in storage "which we did in goodwill in a separated area of the storage facility".
The company said the raw material was not purchased by it and did not reach the food chain through Freeza Meats.
The spokesperson added: "We have under legal jurisdiction been required to detain the product in quarantine awaiting the direction of the local Environmental Health Office".
The spokesperson also said: "All tests that have been carried out routinely on our own finished products i.e. (burgers) have been negative. There have been no traces of equine DNA in any samples taken from Freeza Meats products".
Last night the FSA said it tested a quantity of frozen meat in a cold store at Freeza Meats, which "is potentially linked to the Silvercrest factory" in Co Monaghan.
A statement on the agency's website said of the 12 samples that have been tested, two have come back positive for horse meat at around 80%.
The FSA has launched an investigation into the traceability and source of the frozen meat, which had not entered the food chain.
Investigations by gardaí and departmental unit
Meanwhile, Minister for Agriculture Simon Coveney told an Oireachtas committee hearing on the contamination of beef burgers with horse meat that if there is fraudulent activity going on, it will be detected by the gardaí.
Investigations are under way by gardaí and the special investigations unit at the Department of Agriculture.
Two companies, Rangeland Foods and Silvercrest Foods, in Co Monaghan, both bought products from a meat trading company based in the Republic.
Later, both companies were found to have horse meat on their premises.
Mr Coveney told the Oireachtas Joint Committee on Agriculture, Food and the Marine that he asked gardaí and his department’s special investigation unit to become involved.
Call for independent inquiry
Earlier, Fianna Fáil called for an independent investigation into the horse meat controversy.
Agriculture Spokesperson Éamon Ó Cuív said the longer the crisis goes on, the more damage is being done to a high premium, high-quality industry.
Mr Ó Cuív was critical of Mr Coveney's handling of the controversy, particularly the lack of information.
Irish Farmers' Association President John Bryan has described the latest controversy as a "sorry saga".
Mr Bryan said that while the minister was in Europe trying to negotiate a deal for Irish farmers, what he called rogue traders in meat and rogue processors, had been damaging Ireland's reputation.
He condemned meat processors who are willing to buy products, the authenticity of which cannot be verified.
He added: "To have someone here for the quick buck willing to damage our standards here and willing to buy a product from a trader, certainly that we cannot check the authenticity of his product and put that into a box and label it as Irish is absolutely unacceptable.
"It's unacceptable for a person doing business in Ireland and it's letting down Irish farmers."
Taoiseach Enda Kenny has said the horse meat controversy needs to be dealt with.
Asked whether the Government still believes the material came from Poland or was merely labelled as Polish, Mr Kenny said it was clear that a plant in Poland supplied material but other investigations might have to take place.
Horse meat being 'drip-fed' into burger industry
Meanwhile, the Chief Executive of the Food Safety Authority has said somebody is "drip-feeding" horse meat in the burger manufacturing industry in Ireland.
Speaking on RTÉ's Morning Ireland, Prof Alan Reilly said there is some level of fraud going on and that is why gardaí have been called in to investigate.
He said it was no longer about trace amounts of horse DNA in products, but there was actual horse meat in burgers.
Prof Reilly said the net was "tightening" but the investigation still has some way to go.
He also stressed that the Polish authorities had not formally come back to the Irish food authorities.
Meanwhile, Supermac's Chief Executive Pat McDonagh, which is supplied by Rangeland, has said he is satisfied that the company is using 100% Irish beef in the product supplied to his fast food chain.