New South Wales Police will be cracking down on supermarket security at self-service checkouts, saying plain-clothes officers will be watching customers.

Detective Superintendent Murray Chapman said officers will be running a number of covert operations involving closed circuit camera filming, local police and loss prevention officers in plain clothes.

He reminded people that committing this kind of offence is a crime, no matter how small people think it is.

"Even if it is the avocado and you think you're saving $2, it's still shoplifting," Superintendent Chapman said.

"It's still stealing, it's still a crime and if we catch you, or you get caught, you will be charged."

Police would not comment on the ways in which people were stealing, whether they were not scanning items or scanning them as something of a lesser value.

'Substantial number' of thefts from self-service

Coles spokeswoman Martine Alpins said the supermarket had experienced a "substantial number" of shoplifting thefts from self-service checkouts.

She said of the 6,743 shoplifting apprehensions in NSW since January, 2,697 of those were from the self-service counters.

Detective Superintendent Chapman said there had been 11,000 legal cases relating to shoplifting across NSW last year alone, but did not comment on whether theft numbers had increased specifically due to self-service checkouts.

"You're very vulnerable to being caught for committing this kind of offence no matter how small you think it is," he said.

"We will be targeting, identifying and prosecuting shoplifters.

"You won't see the loss prevention officers visibly at a lot of centres and you won't see the police visibly."

'The security guard was watching me the whole time'

James, who preferred not to give his surname, said he had been caught for theft at a self-service checkout.

Self-service checkouts have become a target for shoplifters, police say. ( ABC News: Raveen Hunjan )

"I noticed that I had a pack of batteries still in my basket, so I just basically put it in my bag thinking, 'oh whatever, should get away with it'," he said.

"Turns out the security guard was watching me the whole time.

"She took me upstairs and I just pleaded ignorance — I said I thought I scanned it — and they didn't call the cops luckily."

He said he had not tried to steal anything since.

"I like to think I'm more honourable now," he said.

Theft costs 'pushed onto the customer'

National Retail Association chief executive Dominique Lamb said theft cost the Australian retail industry $4.5 billion each year, or about 2.2 per cent of annual retail turnover.

Number of Coles shoplifting apprehensions this year: New South Wales: Total: 6,743

Total: 6,743 Self-serve: 2,697 Queensland: Total: 3,173

Total: 3,173 Self-serve: 1,714 South Australia: Total: 3,667

Total: 3,667 Self-serve: 1,687 Victoria: Total: 5,057

Total: 5,057 Self-serve: 2,174 Western Australia: Total: 3,800

Total: 3,800 Self-serve: 1,292 Australia: Total: 22,440

Total: 22,440 Self-serve: 9,564

Ms Lamb said the customer ultimately bears the cost of theft and it could lead to job losses in the industry.

"It's being pushed onto the consumers," she said.

"Retailers have absolutely no option but to push the prices up in order to take into account the money that they've lost.

"This in the end will impact the bottom line and we're likely to see job losses as a result."

Teams of up to 50 stealing

Ms Lamb said some teams of up to 50 people coordinated to steal from stores.

"More importantly, it's got to do with organised retail crime that's occurring," she said.

Ms Alpins said Coles had caught more than 22,000 people shoplifting nationally and just under half of them were stealing from self-service counters.

"We'd like to say to people, stealing is stealing. It doesn't matter how you do it, theft is theft," she said.

Despite the theft, Ms Lamb said Coles had experienced an increase in sales since the implementation of self-service checkouts.

Earlier this year, research showed the rise of self-service checkouts was prompting more people to steal.