Sainsbury's will become the first of the big four supermarkets to stop selling eggs from battery caged hens,
The move from the third largest supermarket chain to only sell eggs from uncaged hens is a major win for poultry welfare groups, and comes three years before an EU-wide ban on battery produced eggs comes into force.
Sainsubry's said more than half a million hens would no longer be kept in battery cages while 2.5 million fewer battery farmed eggs would go on sale each week in the UK.
The supermarket had promised to start phasing out the sale of battery eggs in 2010, but in bringing forward its plans, poultry campaigners said it had marked itself out from competitors Asda, Tesco and Morrisons.
Rowen West-Henzell, food business manager for Compassion in World Farming, said: "It's fantastic news. When Sainsbury's makes a move like this it has huge impact, making animal welfare more mainstream.
"They are doing the right thing on behalf of the consumer. My question to the other retailers is why aren't they responding? They've got a lot of catching up to do."
Under new European legislation conventional battery cages will be banned in 2012. Poultry farmers will be allowed to build larger "enriched" cages which give hens more space. But Sainsbury's is doing away with cages altogether.
Ms West-Henzell said: "This is crucial for us. The birds will be able to flap their wings, run about, peck and scratch, and behave naturally."
Sainsbury's decision follows similar moves by Marks & Spencer, Waitrose and the Co-op.
It also coincides with a renewed campaign by chef Hugh Fearnley Whitingstall to take on Tesco and its poultry welfare policy as part of new Channel 4 series, The Great British Food Fight, which airs in two weeks.

In a David versus Goliath encouter, the animal lover from River Cottage picks up where he left off last year on his free-range chicken crusade and takes on the might of Tesco in an attempt to make it reconsider its animal welfare policy on poultry.
In order to stay ahead of its competitors, Sainsbury's is also aiming to stop using caged eggs as ingredients in own-label food and drink by 2012. Its already only uses free-range eggs in its Its Kids and Taste the Difference ranges.
Morrisons has committed itself to sell only own-label cage-free eggs by 2010.
Sainsbury's egg buyer Finbar Cartlidge said: "We are delighted that all Sainsbury's shoppers will now enjoy higher welfare eggs whilst the other major retailers still continue with over half their eggs coming from caged hens."
People in the UK eat about 10 billion eggs a year.
According to the RSPCA, there are about 30 million egg laying hens, with 63% in battery cages, 31% living free-range and 6% in barn systems.

Sainsbury's bans battery eggs - Times Online