The supermarket giant has been handing out bags to customers in NSW, Victoria, Queensland and Western Australia since July 1 when it brought in a ban on single-use plastic bags and told customers they'd have to pay for reusable bags.

Coles was meant to stop providing its reusable Better Bags for free on August 1 and start charging customers 15 cents per bag, but has now backflipped on that decision and appears set to provide them indefinitely.

Greenpeace criticised the decision as irresponsible and disappointing, saying that Coles is perpetuating the problem of plastic waste by providing free bags.

"They talked the talk but haven't walked the walk," spokeswoman Zoe Dean told AAP on Wednesday.

"It's interesting because the ban on single-use bags came as a result of pressure from customers and people calling for companies to take responsibility and stop using plastic bags.

"While a minority of people are struggling to cope, we know it's just a matter of time for people to adapt to the change."

Some shoppers took to social media to attack Coles.

"What a bunch of cowards you are @Coles you should be doubling down and not making any plastic bags available in your stores," Ben B tweeted.

Sally Edsall was also displeased.

"Hey Coles, I won't be shopping at Coles until you stop this plastic bag nonsense," she tweeted.

Retail expert Associate Professor Gary Mortimer added : "#Coles claim it 'is continually looking at ways to reduce plastic, which is why we removed single-use plastic shopping bags on July 1...' Really? Very disappointing."

A Coles spokeswoman said when the ban on single-use plastic bags came in, some customers said they needed more time to transition to reusable bags.

"We've been delighted to see customers grow more accustomed to bringing their reusable bags from home so they are relying less on complimentary bags at the checkout," she said in a statement.

"Many customers bringing bags from home are still finding themselves short a bag or two so we are offering complimentary reusable Better Bags to help them complete their shopping."

Coles and rival Woolworths both recently banned single-use plastic bags and began selling reusable bags instead.

Coles originally said it would provide its Better Bags, made from 80 per cent recycled material, for free until July 8 to help customers adjust.

But Coles then decided to extend the giveaway of free reusable bags until August 1.

Woolworths also offered customers free reusable bags until July 8.

Both supermarket chains faced a backlash from some shoppers after their bans on single-use bags were introduced as part of a national push to reduce plastic waste.

Australian Associated Press