Australians are losing faith in the nation’s supermarket giants as shoppers in more states are forced to trade up their single-use plastic bags for greener options, a university study reveals.

Nearly 30 per cent of the 500 Australian shoppers surveyed considered switching to a competitor as a result of the bag change, the Monash University data shows.

There has been a 6 per cent drop in consumer trust in supermarkets from May to August – between which some Victorian retailers phased out single-use bags – a quarterly survey found.

Most of the Woolworths and Coles shoppers surveyed across the country said they would switch to the other, as a result of changes to their bag policies in Victoria, the Monash Australian Consumer Retail and Service research unit’s quarterly survey found.

Participants in the online survey were asked about their faith in the supermarkets to do the right thing and whether they had considered switching their main supermarket due to the changes in the plastic bag policies.

Research consultant Paolo De Leon said Aussie retailers retained trust by having policies in the customers’ best interests and solving problems.

“The removal of single-use plastic bags and subsequent confusion with inconsistent policy changes from both major supermarkets has created more problems than it has solved,” Mr De Leon said.

“Major supermarkets, such as Coles and Woolworths, rate reasonably lower on these key attributes since May, particularly when we see consumer backlash related to the single-use plastic bag ban and also the extension of complimentary multi-use plastic bags.”

Despite the fall in trust levels, customers continue to give business to the supermarket giants.

“Shoppers’ behaviours will not change that easily,” Monash’s head of marketing, Professor Harmen Oppewal said.

-AAP