Sainsbury's sells nearly 600 million eggs a year and the scale of the move represents a major shift away from caged eggs in the industry.

Rowen West-Henzell, Compassion in World Farming's Food Policy Officer, said: "Sainsbury's move today signals a sea change in policy on shell eggs for all the top retailers and demonstrates how seriously it takes its ethical responsibility. We're thrilled that Sainsbury's has taken the opportunity of the Good Eggs initiative to make this commitment."

Mike Coupe, Sainsbury's Trading Director, said: "We are working to phase out all of our caged eggs ahead of 2012, and are currently working with our suppliers to achieve 100% UK cage-free eggs as soon as possible.

"Sourcing with integrity is extremely important to Sainsbury's, and making this pledge to sell only cage-free eggs reflects our priorities in sourcing ethically, and addressing the concerns of our customers.

"Sainsbury's is delighted to receive the Good Egg award which recognises the progress we've made regarding the 1.6 million eggs we sell every week."

Sainsbury's is committed to the health and welfare of the animals reared to produce its food and drink. As a retailer with 16 million customers a week, making scale changes in how its eggs are produced by the many farmers involved, requires considerable forward planning.

One such initiative is Sainsbury's 'Woodland Eggs', with its innovative welfare standards, including the planting of over 1 million trees. The trees help to create an environment where hens feel more secure, with the freedom to roam. Sainsbury's ‘Woodland Eggs' hens spend far more time outside, venture further from their barns and in greater numbers. This has really helped the welfare and well-being of the hens.

Compassion in World Farming advocates that the best free-range system for laying hens is providing tree cover. This is because hens originate from jungle fowl and still, to this day, fear aerial predators. Tree cover and vegetation encourages them to range outside without feeling afraid.