OTTAWA, Ontario – The Canadian Food Inspection Agency expanded a nationwide recall of frozen beef burgers on concerns the product may be contaminated with E. coli O157:H7.

The CFIA is now warning the public not to consume Cardinal brand Prime Rib Beef Burgers, sold in 1.13-kg. packages bearing UPC 0 63351 01561 1 and BEST BEFORE 2013 JL 31 EST 752.

Cardinal Meat Specialists Ltd., Brampton, Ontario, manufactured the burgers and continues to be the subject of a CFIA food safety investigation. CFIA has not reported any problems at the plant so far, and the burgers have not been definitively linked to the illnesses, according to the agency.

“This recall is the result of an ongoing food safety investigation being conducted at Cardinal Meat Specialists Ltd.,” the agency said in a statement. “This investigation was initiated as a result of recent product testing associated with an outbreak investigation. There may be recalls of additional products as the investigation at this facility continues.”

The Public Health Agency of Canada (PHAC) notified CFIA that a small cluster of E. coli O157:H7 illnesses were reported in Ontario and Alberta. PHAC said the illnesses were potentially linked to the Butcher's Choice Garlic Peppercorn Beef Burgers made by Cardinal Meat Specialists. The CFIA subsequently launched a food safety investigation, which included extensive testing of retail samples from across Canada. Preliminary results identified two presumptive positives for E. coli O157:H7 in one lot of frozen hamburgers, CFIA said.