Wrap has praised retailers' efforts to reduce the impact of plastic bags, as many have also increased the content of recycled plastic in their bags and reduced the weight.
Overall, Wrap said the environmental impact of bags had been reduced by 40% since 2006, exceeding the target of 25% by the end of 2008 agreed between Government and industry in 2007.
But the 26% reduction in bags used falls far short of the cut the Government called for in November when it introduced legislation allowing it to impose mandatory charging. Supermarkets have agreed to the Government's target of a 50% reduction in bags handed out by May this year in a bid to stave off charging.
Polling for the Daily Mail, which is running a 'ban the bags' campaign, suggests consumers overwhelmingly support mandatory bag charging. Some 83% of consumers believe shops should stop giving bags away, while 82.1% support a 10p-15p charge.
Bag use at M&S has fallen more than 80% since it introduced mandatory charging in May last year, saving the retailer an estimated £11m a year. M&S said any cost savings were reinvested in its Plan A eco-scheme.