From today, Pak n Save and New World will turn anyone away who is not wearing a mask.
Owners Foodstuffs says the rule will apply to all of its different store brands.
Masks are now compulsory for staff and customers at supermarkets, petrol stations, dairies and pharmacies.
Countdown says it won't enforce the new rules because it doesn't want to endanger its staff.
Conan Young reports.
