Grocers have reduced the number of single use carrier bags being handed out for the fourth year in a row through independent monitoring.

Over the same period, the total weight of material used in carrier bags has more than halved. With sales volumes having rise by more than 6% since 2006, this achievement, says the British Retail Consortium (BRC), is a "ringing endorsement" of the voluntary approach adopted by the supermarkets and negates the need for compulsory bag bans or taxes. The business group believes retailers should be allowed to use a range of methods that work best for their own customers.

In the year to May 2010, 43% fewer single use bags were handed out than in 2006. When bags of all types are counted, the reduction over the same period is 41% - demonstrating that this is a genuine gain not simply a case of thin plastic bags being replaced by other types.

The results were revealed yesterday by the BRC, whose participating members had their results independently monitored by WRAP.

BRC director general Stephen Robertson said: "This is a tremendous achievement by supermarkets, customers and staff, especially as between 2006 and 2009 the amount of goods sold by participating retailers grew by over 6%. The sustained reduction shows that customers are permanently adopting the habit of re-using their bags.

"The continuous decrease in total annual bag use demonstrates the voluntary approach continues to make good progress through individual retailer initiatives that take customers with them.

Mr Robertson added: "The reduction in bag use is great news, but it's the halving of the total weight of single-use carrier bags, which shows retailers really scoring on the crucial issue of reducing environmental impact.

The news follows an announcement that the Welsh Assembly Government is I the process of pushing through a 7p charge on single use carrier bags. Business groups have criticised the move, which could see the charge come into effect as early as March 2011. If retailers don't impose the charge when it comes in, they could face a £25,00 fine.