Plastic bag usage fell by 26 million last year
The number of carrier bags in use in Northern Ireland fell by 26 million last year.
Major supermarkets have been encouraging customers to take in reusable bags to save waste.
Environment Minister Alex Attwood has launched a public consultation seeking views on charging for bags.
"I fully acknowledge and welcome the success of voluntary efforts in reducing the number of bags in circulation," he said.
"In Northern Ireland the number of bags handed out by major supermarkets in 2010 fell by 26 million. The introduction of a bag charge will build on the good work already under way."
However, the head of the Northern Ireland Independent Retail Trade Association, Glyn Roberts, said: "We have real concerns that this levy, far from protecting the environment, will actually cause it greater harm as proven in the Republic where more consumers are buying black plastic bin liners - which take 1,000 years to biodegrade in landfill - because single-use bag usage has dropped."