Fonterra is investigating why Lower North Island customers have been reporting that their milk tasted funny.
The company has recalled several batches of Anchor blue top bottles sold with best before dates of late June.
Fonterra Brands Managing Director Leon Clement says there's no safety risk, but they've removed the affected milk from their supply chain, and will be thoroughly investigating.
In a statement, Mr Clement said there has been a "quality issue limited to a few batches with best before dates 21-27 June."
"We encourage customers who have blue top that doesn't taste as good as it should to contact our customer care team," he added.
One shopper says staff at Thorndon New World in Wellington were warning customers the recalled milk was contaminated.
The shopper attached a photo from the supermarket, which said Value Standard blue top milk had also been recalled.
Thorndon New World staff warning shoppers : Anchor Standard Milk is contaminated. Pulling it from shelves pic.twitter.com/k6YphOqjM6— Kent Atkinson (@kentatkinson) June 15, 2017