Environmental groups are annoyed with the supermarket chain Coles' decision to not only continue handing out plastic bags to shoppers, but also for switching to a thicker plastic that is worse for the environment.

"Some customers told us they needed more time to make the transition to reusable bags," a Coles spokesperson told the ABC.  "We will continue to listen to our customers and our team members on an ongoing basis to assess when customers have become accustomed to bringing their own bags, and will provide them with as much notice as possible," the spokesperson said.

Coles had promised to phase out plastic bags from 1 July, and most state governments have banned or are in the process of banning them.  But now, thicker reusable bags which had previously cost 15 cents each will be handed out for free. 

The environmental group Greenpeace says this is an awful idea.

"Coles have caved in far too quickly to a small but vocal minority and there is absolutely no doubt Coles will be punished for this decision by customers who don't want to see plastic bags littering their beaches and killing marine life," Australia Pacific campaigner Zoe Deans said. 

If the thicker plastic bags are haphazardly discarded, they'll cause a bigger problem than the previous single-use bags because they take even longer to break down.

"This decision makes a complete mockery of Coles' claim to want to reduce plastic waste and is a betrayal of the millions of their customers who want the supermarket to do the right thing in favour of a vocal minority," Ms. Deans said.  "Removing the price means that these reusable bags are far more likely to be used once and discarded."