Horsemeat found in burgers came from imported ingredients, the Agriculture Minister Simon Coveney has confirmed.
The minister said results from tests showed that the DNA came from raw material brought into the Silvercrest Meat plant in Ballybay, Co Monaghan from another EU member state.
He also reaffirmed that tests on samples taken from Irish food ingredients were negative and said he was pleased the integrity of Irish food production had been maintained.
The intensive investigation launched by the department and the Food Standards Authority of Ireland (FSAI) sourced the equine DNA to Poland.
More than 140 samples of primary products and ingredients were tested. Three burgers and one imported ingredient tested positive for significant levels of horse meat.
The Minister said there had been engagement with senior figures from ABP Food Group which operates the Silvercrest plant. The findings of the official investigation show that they did not deliberately use horse meat in their production process.
Silvercrest is owned by the Larry Goodman ABP Food Group, operator of the Dalepak facility in Yorkshire, England which was also found to have supplied supermarket products with traces of equine DNA.
It was one of two Irish food processing plants linked to the horse DNA controversy. Samples from a range of beef burgers produced between January 10-16 were tested. More than 10 million burgers have been taken off shop shelves across Ireland and the UK.
According to food safety and government officials, there was no health issue with traces of horse meat or DNA being found in meat products from the processing plants and being sold in supermarkets Tesco, Dunnes Stores, Aldi, Lidl and Iceland.
It is understood a deep cleansing operation has begun at the premises in Co Monaghan which are now under new management. Paul Finnerty, group chief executive of ABP said: "While the company has never knowingly purchased or traded in equine product, I wish to take this opportunity to apologise for the impact this issue has caused."