The Canberra Liberals are promising to overturn a ban on free plastic shopping bags if they win October's election.

Since last November, shoppers have been forced to use reusable bags, and retailers have faced penalties if they flout the rules.

Earlier today Liberals Leader Zed Seselja said he would consider lifting the ban on plastic bags as an election policy.

But he now says his party will definitely scrap the ban if it is elected.

"I'm giving Canberrans back the choice they deserve. If businesses have adapted to the ban and would like to continue charging for bags, they are welcome to do so. But if they don't, they won't be lumped with a $27,500 penalty," he said.

A review of the bag ban is scheduled for November, with the Government saying a year's worth of data is needed to make the review effective.

But Mr Seselja wants the review conducted before voters head to the polls.

"I don't think it has been a success. We were very sceptical of it at the time, that's why we voted against it," he said.

"The evidence said that it actually didn't improve environmental outcomes. The Productivity Commission said that and so I think it's important that the Government puts all of the information on the table rather than keeping it secret until after the election."

'Gold-medal backflip'

Environment Minister Simon Corbell says the Liberals are being hypocritical.

"When it comes to backflips this is a gold-medal performance by Zed Seselja," he said.

"In 2003 the Canberra Liberals wanted to ban plastic bags, they wanted Canberra to be plastic bag free by 2006.

"Now they're promising to overturn a ban they previously wanted. They just can't be trusted on these issues."

Mr Corbell says there is anecdotal evidence the ban is making a difference.

"Anecdotally we are seeing significant behaviour change from consumers. People are doing the right thing, being proactive, they're reducing the use of plastic bags, they're relying on reusable bags that have less impact on the environment," he

"But we'll conduct a thorough review."

Greens MLA Shane Rattenbury says lifting the ban would be a backward step.

"The evidence clearly shows at this point that this is a good way to go," he said.

"Certainly the research we've done, and we've contacted all of the supermarkets in the ACT, they have indicated to us that plastic bag use has declined since the ban came into effect.

"I suspect the review will show the policy has been quite effective. It may also show some areas where we can make some adjustments."