British supermarkets have pledged to reduce the number of single-use carrier bags they hand out to shoppers to half the level it was in 2006 by this spring, a move which could accelerate the cultural shift in consumers' attitudes to free bags.

Last month Asda, Co-op, Marks and Spencer, Sainsbury's, Somerfield, Tesco and Waitrose all reached an agreement with environment minister Jane Kennedy to cut their use.

"This is a bold commitment which will result in about five billion fewer bags being handed out," said Kennedy. "Supermarkets have already taken some imaginative steps to help us use fewer carrier bags."

If its target is achieved, the number of bags saved would be enough to fill 60 Olympic-sized swimming pools. The agreement will be monitored by the Waste & Resources Action Programme (WRAP) and reviewed again in the summer of 2010.

Small stores have led the way in plastic bag reductions. The East of England Co-op claims to have cut the number of bags it uses by seven million since it stopped handing them out in September last year.