The recall first announced Saturday applied only to four-litre bags of chocolate milk sold in Ontario and Quebec with a June 1 best before date.
The recall now includes milk with expiry dates up to June 22 and includes all sizes of Neilson chocolate milk made at its Georgetown, Ont., plant until production stopped late Friday.
The move followed a positive test on one of 70 random samples taken by the Canadian Food Inspection Agency at a supermarket.
Although no additional samples tested positive, the Montreal-based company said it expanded the recall out of caution.
Saputo spokeswoman Sandy Vassiadis says the company is investigating.