OTTAWA -- The Canadian Food Inspection Agency first became aware of problems with beef produced at an Alberta company when tests conducted in the U.S. came back positive for E.coli.

Agency spokesman Garfield Balsom confirmed that word of the positive findings came from the Food Safety Inspection Service of the U.S. Drug Authority on Sept. 3, nearly two weeks before the CFIA began issuing advisories about ground beef products produced at Edmonton-based XL Foods.

Balsom said XL initiated the recall on its own, insisting it was not ordered as a result of the U.S. test results.

"There were some positives identified by the FSIS, but the positives were not the trigger for the recall," Balsom said in a telephone interview. "The recall was a voluntary recall by the company."

A statement on the FSIS website said both the service and the CFIA conducted followup tests on the beef products, which were distributed in eight states.

The FSIS has issued a public health warning about the contaminated meat and said it's working to ensure all affected products are pulled from store shelves.

The international twist is the latest development in a recall that has already spread from coast to coast and depleted meat supplies at nearly all the country's major grocery retailers.

The CFIA issued yet another expansion to a recall of ground beef products made by Edmonton-based XL Foods on Friday, extending an advisory whose scope has grown almost daily since it was first issued on Sept. 16.

The latest additions to the growing list involve not only packages of ground beef, but products prepared with the meat suspected of containing E. coli. Those include sausages, meat loaf, meat balls and burgers.

Unbranded meat products carried at Walmart locations in Manitoba, Saskatchewan, Alberta and British Columbia have officially been recalled, the CFIA said. The other products included in the expanded advisory were sold at Metro locations in Ontario and Safeway stores in all five provinces.

The risk of contamination also exists in unlabelled or unbranded beef products sold at independent shops not covered on the CFIA's advisory, the agency said.

The CFIA urged consumers who are unsure if they have the affected ground beef product in their home to check with the store where the product was purchased or throw it out.

Walmart is just the latest of the country's food retailers to feel the effect of the recall.

Previous announcements from the CFIA said affected beef products have been distributed in all 10 provinces as well as parts of northern Canada.

Retailers forced to pull the products from their shelves include Sobeys, Co-op, Foodland, Giant Tiger and several corporate and franchised Loblaws Companies stores such as Real Canadian Superstore and Your Independent Grocer.

Balsom said no E. Coli cases in humans have been linked to tainted meat, setting this recall apart from the deadly listeria outbreak that forced grocery stores to yank thousands of Maple Leaf Foods products from their shelves in 2008.

"The Maple Leaf was a reaction to an outbreak that was currently ongoing in Canada. We have no outbreak at this point, no illnesses linked to this product."

The Public Health Agency of Canada confirmed that no current E.coli cases have been connected with the tainted meat.

Authorities at Alberta Health Services said they are currently probing five individual E.coli cases -- four in Edmonton and one in Calgary -- but said they have not established a link to the CFIA recall.

PHAC said it is not aware of E.coli incidents anywhere else in Canada.

XL Foods did not respond to requests for comment.

Balsom urged Canadians to be vigilant about checking any of their recent ground beef purchases to see if they have been included in the recall.

A complete list of affected stores and products can be found on the food inspection agency's website at www.inspection.gc.ca.