Including bags for life and cotton bags the figure fell to a 1.5% reduction year-on-year and 44% compared to 2006.

The spot data for the month of May 2010 showed a 5% increase in the number of bags that were given out by retailers compared to 2009, although the figure is still 45% down on 2006.

The British Retail Consortium hailed the "tremendous achievement" in reducing bag use against the background of a 6% increase in the amount of goods that retailers sold between 2006 and 2009.

Successful voluntary scheme
BRC director general Stephen Robertson said the figures showed the voluntary approach was working.

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

Asda, Marks & Spencer, Sainsbury's, Tesco, Waitrose and the Co-operative Group – which includes Somerfield – are the retailers that are participating the voluntary carrier-bag agreement.

"This shows the outstanding success of the voluntary scheme and great credit must go to retailers and consumers for demonstrating that a voluntary route is far preferred to punitive bag taxes," he said.

His view was echoed by Barry Turner, chief executive of the Packaging and Films Assocation (Pafa).

Turner said: "We should also not lose sight of the real carbon footprint of a single carrier bag which is extremely low due to the efforts of our industry. One car trip to the supermarket is equivalent to two years consumption of single-use bags."

Welsh carrier-bag charge
Environment minister Jane Davidson agreed that the voluntary system had "dramatically helped reduce the number of bags we use", a more formal agreement was needed.

Davidson said that the charge that is due to come in next year would provide the incentive for further improvement.

"Wales is already doing slightly better than the rest of the UK," said Davidson.

"I think this is not only down to the efforts of retailers and people across Wales, but also to discussion, publicity and general momentum ahead of the introduction of the carrier-bag charge in the spring."