A large recall of Neilson brand chocolate milk is being expanded over worries about Listeria contamination.

There have already been illnesses that may be linked with drinking these milk products, the Canadian Food Inspection Agency reports. Further lab testing is underway to confirm the link.

Saputo Inc. announced on Saturday it was recalling four-litre bags of Neilson brand partly skimmed chocolate milk sold in Ontario and Quebec.

On Sunday night, the recall was expanded to include additional packages of the milk, after the CFIA conducted a food safety investigation.

The recall now includes the 2-litre and 1 litre cartons, and the 750 ml, 473 ml, and 237 ml sizes.

All had Best Before dates up to and including JN22, and all were manufactured at Saputo's Georgetown, Ont. facility (Plant registration # 1590).

“The Plant Registration Number ‘1590’ that appears on packages can assist consumers in identifying the affected products,” the CFIA said.

Anyone who finds the recalled products in their homes should throw it out or return it to the store where they were purchased for refund.

“If you think you became sick from eating or drinking a recalled product, call your doctor,” the CFIA advises.

Food contaminated with listeria can cause vomiting, nausea, persistent fever, muscle aches, severe headaches and neck stiffness.

Most recover from listeriosis, but the infection can lead to premature delivery or stillbirth in pregnant women. It can also be fatal in the elderly and people with weakened immune systems.

The CFIA says it is continuing its safety investigation, which may lead to other products being recalled.