Canada's food inspection agency has failed to find a link between Australian or New Zealand beef and E.coli in frozen hamburgers that sickened five people.
Beef products, produced by Canada's Cardinal Meat Specialists Limited, were recalled between December 12 and 15 after a "small cluster of illnesses" in Ontario and Alberta.
The Canadian Food Inspection Agency (CFIA) investigated whether beef imported from Australia and New Zealand used in the burgers could be the E.coli source, but found it met all import certification and testing requirements.
There was also no confirmation of illness in Australia or New Zealand from E.coli with the same genetic fingerprint.
The investigation also looked at spices and Canadian beef ingredients in the burgers, but they also tested negative for E.coli.
"As all lines of inquiry have been exhausted, the CFIA's investigation will not progress further," the CFIA said in a statement.