The factory linked to a deadly nationwide listeriosis outbreak will not reopen today as planned, announcing Tuesday that is has postponed reopening until at least Thursday.

Maple Leaf Foods has spent the past week sanitizing the North York factory that produced the tainted meat, but decided to remain closed.

Representatives say the company will reassess its decision to resume operations on a daily basis, and will conduct more testing of their products before sending anything out.

The announcement comes the morning after health officials announced that 12 people have now died and 26 are ill from listeriosis linked to tainted meat from the Maple Leaf Foods plant in North York.

The Canadian Food Inspection Agency (CFIA) is determining if listeria bacteria was the sole cause of death in half of those fatalities. All but one of the fatal cases were in Ontario and one was in B.C.

Test results announced over the weekend linked the outbreak with meat produced by Maple Leaf Foods that was tainted with the listeria bacterium. Maple Leaf Foods has recalled more than 240 products made at the plant.

Meanwhile, a Montreal-based law firm says it has been approached by at least 300 people interested in launching a class action suit against Maple Leaf Foods. Merchant Law Group LLP said it planned to launch lawsuits in Quebec, Ontario, Manitoba and Saskatchewan on Monday afternoon. Lawyers said that they were getting 20-30 calls an hour about the suit.

Health officials are warning Canadians to throw away any meat that comes from uncertain origins, and to avoid pre-packaged sandwiches that contain deli meat.

Early Tuesday, the CFIA said Atlantic Prepared Foods Limited is recalling three sandwich brands sold in New Brunswick, Prince Edward Island and Nova Scotia -- Irving, Sub Delicious and Needs brand sandwiches.

Metro Ontario Incorporated has pulled Fresh 2 Go sandwiches from A & P and Dominion stores for the same reason.

In Alberta and Saskatchewan, Safeway and TakeAwayCafe brand sandwiches have been removed by Lucerne Foods.

Products with the establishment code of "97 B" printed on the label are the meats affected by the recall. Consumers who have purchased such products can obtain a refund by returning the items to the retailer.

Experts say the recall will cost the company an estimated $20 million, its stocks plummeting sharply on Monday after the contamination link was confirmed.

Listeriosis is a rare but potentially serious food-borne illness. Its symptoms include high fever, severe headache, neck stiffness and nausea. Pregnant women, the elderly and people with weakened immune systems are particularly at risk.

Public health officials say they expect the number of cases to continue to grow in the next few weeks as the bacteria has an incubation period of up to 70 days.

For complete lists of the meat products recalled by Maple Leaf Foods, visit the CFIA website here.

With files from The Canadian Press