About 6,500 tonnes of plastic will be saved annually, Sainsbury's says.

The new orange bags will be phased in from next month and save 6,500 tonnes of plastic a year, the supermarket group said.

Sainsbury's currently gives out 1.7 billion white carrier bags annually. They will be phased out by February.

Earlier this month the firm said that 500 of its own-brand goods would be in packaged in compostable materials.

'Passionate issue'

The announcement by Sainsbury's is the latest in a string of "green" innovations unveiled by retailers.

Tesco plans to introduce biodegradable carrier bags this month, and is offering loyalty points to customers who reuse their old bags - even if they are from rival stores.

US grocery giant Wal-Mart - which owns Asda in the UK - has said it will cut packaging by 5% over five years from 2008, while Swedish home furnishings group Ikea has started charging for its bags.

The new Sainsbury's bags will be made up of 57% raw plastic and 10% chalk as well as the recycled material, the company said.

Carrier bags were a "passionate issue" for shoppers, Sainsbury's chief executive Justin King said.

"This is a major green step forward because recycling carrier bags, very much like lots of our packaging, means we're cutting down on the use of plastic as well as what goes to landfill," he said.