Coles and Woolworths have defended the decision to film customers at self-checkouts despite outrage over the new surveillance technology.
Customers of the Australian supermarkets have been noticing the new cameras throughout stores, aimed at catching people stealing products.
Many said they were shocked to discover they were being filmed and have raised privacy concerns.
But the supermarkets have defended the hidden cameras, saying it is to stop people from stealing billions of dollars worth of goods every year.
The Global Retail Theft Barometer reported that Coles loses an estimated $891 million per year in theft, meanwhile Woolworths loses up to $1billion per year.
A Coles customer noticed large screens above the self-serve checkouts while he was shopping
A man posted images of similar surveillance at Coles, but the supermarket has larger screens above the self-checkout rather than the smaller option at Woolworths
Branwell Travers was shopping at Fitzroy Woolworths, in central Melbourne, when he noticed a recording of himself on the screen.
'For how long has Woolworths been filming me while using self-checkouts?' he tweeted.
Woolworths said the surveillance was a new security measure aimed at keeping customers accountable.
The spokesperson told Daily Mail Australia: 'We know the vast majority of our customers do the right thing at our self-serve checkouts.
'This is a new security measure we're trialling for those that don't.'
The spokesperson said the vision is a digital reflection of the customer that is not recorded.
The cameras cannot view the PIN pad and comply with payment and security standards and it is unclear how many stores are trialling the new system.
Another man posted images of similar surveillance at Coles, but the supermarket has larger screens above the self-checkout rather than the smaller option at Woolworths.
A customer was shocked to discover he was being recorded (pictured above) at a Woolworths self-serve checkout in Fitzroy, central Melbourne, this week
He shared an image of a Coles supermarket that had smaller screens displaying a live feed of the customers above the self-service checkout machines.
A Coles spokesperson told Daily Mail Australia: 'While the large majority of our customers do the right thing, it's not fair that a small number of people get away with doing the wrong thing.'
'Coles is currently trialling new security technology in a small number of stores to help us reduce the occurrence of assisted checkout theft.'
Twitter users quickly slammed the security initiative as an invasion of privacy.
One commenter said: 'I won't be using self-service anymore.'
Another user joked: 'Appears to be an 'anti-privacy measure.'