Prime Minister Stephen Harper has promised an independent investigation will be launched into the deadly outbreak of listeriosis that sparked a nationwide recall of meat products.

The announcement came as officials identified a 13th death directly linked to listeriosis found in meat from a Maple Leaf Foods plant in Toronto.

"I know the company has said they take full responsibility. But I'm very troubled by this," Harper said in Windsor, Ont., on Wednesday afternoon. "I'm troubled as a father whose family buys and uses some of these products.

"I'm also troubled as the head of a government that has made substantial investments in our food safety system."

Harper said that when the outbreak is over, the government will appoint an independent arm's-length investigation.

He said the purpose will be to ensure "we get to the bottom on the government's side, on the bureaucratic side, of exactly what transpired and to make sure that as we go forward and we make changes to our system, that this kind of thing can't happen again."

Maple Leaf Foods has issued a recall of virtually all the products produced at the plant, which has in turn triggered dozens of recalls of ready-to-eat sandwiches made from the Maple Leaf products.

Officials say 38 cases are under investigation, with 19 deaths related to listeriosis. But officials say they still believe the worst of the outbreak may be over and few new cases are expected.

Listeria bacteria can be found in unpasteurized dairy products, raw vegetables and meats and processed foods including deli meats and hot dogs. Eating foods spoiled with Listeria monocytogenes can result in serious illness including brain and blood infections and in extreme cases death.

With files from the Canadian Press