The reported deaths occurred among 26 confirmed cases of food poisoning, while Agriculture Minister Gerry Ritz said the government expected more cases in coming days.
The outbreak was triggered by infected meat produced at a plant owned by Maple Leaf Foods, one of Canada's biggest meat processors, which has voluntarily withdrawn about 220 of its products with direct costs to the firm of about 20 million Canadian dollars (US $19 million),
The company hoped to reopen the Toronto plant connected with the outbreak on Tuesday, but health officials are set to test and hold all its meat products until they make sure they are not contaminated.
Listeriosis, a type of food poisoning that is particularly dangerous for pregnant women, the elderly, infants and people with weak immune systems, is characterized with fever, headache, stiffness, nausea, abdominal pain and diarrhea.
The Public Health Agency of Canada has announced listeriosis a contributing factor in seven of the deaths, adding the deaths of five others who had the bacteria in their systems were still under investigation.
Maple Leaf says it is unlikely that it will be able to determine the source of contamination as the listeria bacterium is common and pervasive.
Company president and CEO, Michael McCain, has appeared in a series of national advertisements, offering his deepest sympathies for the outbreak.
Tony Merchant of Merchant Law Group, known for pursuing class action lawsuits, has said his firm will take action against Maple Leaf.
"There are people who are dead, people who are seriously injured. And there are millions of Canadians who are worried about the meat they ate," he told CTV News.