Agriculture Minister Simon Coveney will brief a parliamentary committee on the horse meat controversy today after a second processing plant tested positive for equine DNA.
Police have been called in to assist investigations into the deepening scandal after Rangeland Foods in Castleblayney, Co Monaghan was shut down.
A sample at the factory tested positive with a reading of 75% horse DNA in raw ingredient.
The Minister will join Professor Alan Reilly, whose research at the Food Safety Authority of Ireland (FSAI) first exposed the contamination of processed beef burgers in Irish made products.
Supermacs confirmed last night that it buys its beef burgers from Rangeland Foods.
It said however that it has been assured that its burgers are 100% Irish beef.
Supermacs said that it has written guarantees from Rangeland.
The fast food company said that it has conducted its own independent DNA tests to make sure the burgers it is selling are 100% Irish beef and do not contain horse DNA.
The ABP Food Group, owned by Larry Goodman, has lost contracts worth an estimated €45m with Tesco, Aldi, the Co-Operative Group and Burger King over the fiasco.
The source of the equine DNA, in another case as high as 29% in a burger, has been traced to a factory in Poland.
ABP's plant, Silvercrest, also in Co Monaghan, was found to have been supplying contaminated products.
Mr Coveney will brief politicians on the Oireachtas Joint Committee on Agriculture, Food and the Marine in Dublin this afternoon.
A special investigation unit from the department has been tasked to get to the bottom of the controversy, with support from gardai.
In a statement the Department of Agriculture said production had been suspended at Rangeland, a frozen burger supplier established in 1892 with a turnover of €18m and about 80 staff.
"The company has indicated that none of this product has entered the food chain," the department said.
Inquiries into whether Polish labelled product has been used in other meat processing plants in Ireland are ongoing.
Rangeland called in authorities last Thursday amid suspicions that Polish sourced meat may contain horse.
An Irish-based trader had imported the meat, the department said.
Committee chairman Andrew Doyle said: "Our committee has followed this story with deep concern. Ireland's enviable reputation in producing green, clean and traceable food, so critical to the prosperity of our €10bn agri-food industry, risks being undermined when issues like this arise.
"Our committee are keen to constructively engage with minister Coveney, his officials, and Prof Reilly on the lessons learned from the investigation. It will provide an opportunity to reassure the public on the steps being taken to ensure such a lapse is never repeated."
The committee will decide tomorrow whether ABP should be called in to explain its part in the crisis.
Experts from Britain's Food Standards Agency (FSA) told the Commons Environment Committee last week they could not be sure if contaminated burgers were being sold for more than a year.
At least 10 million burgers were put into storage to be dumped following the scandal.
Controversy and concerns about traceability of food deepened at the weekend when a company which supplied halal food found to contain traces of pork DNA was named by food distributor 3663 as McColgan Quality Foods Limited, a Tyrone-based company.