Major stores have begun clearing their shelves of eggs from caged birds four years before the introduction of an EU law to stop birds being kept in tiny cages.

Sainsbury's, the Co-op and Morrisons have all agreed to ban eggs from caged birds while Marks & Spencer and Waitrose already sell only free-range eggs.

All products containing egg will also use free-range varieties.

The chains will phase out battery hen eggs over the next two years, before an EU ban on battery cages due to come into effect in 2012.

Asda and Tesco have not yet followed suit, but have cut back shelf space given to battery hen eggs.