A 5p charge for carrier bags will be introduced in England next year, but the British Retail Consortium says this will cause confusion for customers.
The BRC says its members have expressed disappointment that Government plans to implement a 5p carrier bag charge will ignore the advice of the industry and a key parliamentary committee.
The Queen confirmed at the state opening of parliament earlier in the month that the charge will come into force on October 1 2015.
However, there are three exemptions to the charge: retailers with fewer than 250 employees, single use carrier bags not made from plastic and biodegradable bags.
The BRC says that exemptions for smaller retailers will make it confusing for customers as they will be made to pay in one shop but not another.
The trade association adds that its SME retail members have made it clear that they do want to be exempt.
A BRC spokesperson said: "A carrier bag charge is already working in Wales and Northern Ireland and will be introduced in Scotland in October and it makes no sense to do something different. Why not use the same scheme and keep it simple and effective?
"If we are to have regulation it needs to work for consumers, the environment and retailers. We are disappointed that the Government has chosen not to listen to the Environment Audit Committee, environment groups and retailers.
"This is poor regulation that will cause confusion for customers and businesses."