Supermarkets shamed by plastic bag overuse in home deliveries

Both supermarkets have used high profile marketing drives and incentives to persuade consumers to use fewer bags.

Tesco has offered extra ClubCard points to customers who bring their own bags while Sainsbury's efforts have included offering a free 'bag for life' and using bags to package cereal rather than cardboard boxes.

However, both retailers used 14 bags to deliver the 29 items. Tesco devoted a bag each to a pack of sausages, a bottle of Fairy Liquid and a packet of mince. Sainsbury's did the same for a six-pack of Walkers crisps.

The other retailers fared little better with Ocado using 10, Asda 9, and Waitrose the most economical with 7 bags.

Sainsbury's said it would investigate why one bag was used to deliver the Walkers multipack while Tesco maintained it gave customers the option of having food delivered in crates.

The use of plastic bags is a continual problem for retailers looking to balance environmental concerns with the practicalities of making it easy for customers to shop.

The latest call for a reduction in the number of bags use has come from the United Nations Environmental Programme, which has called for a worldwide ban on the use of thin film single use bags and said "there is simply zero justification for manufacturing them anymore, anywhere".

The UNEP said the bags were second only to disregarded fishing lines in causing marine wildlife entanglements.

The Carrier Bag Consortium has responded to the UNEP criticisms. Peter Woodall,  head of communications at CBC, said: "Plastic bags are very useful containers and can be recycled. Government statistics show that 80 per cent of all households reuse plastic bags to ensure their waste is hygienically tied up and plastics reprocessing is a very good use of resources as it is endlessly recyclable."