Undercover investigators from Compassion in World Farming looked at conditions on three farms and discovered practices which may breach welfare laws and government guidelines.
They say they found:
The campaign group is to hand a dossier on its findings to Agriculture Minister Nick Brown.
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CIWF campaigns director Philip Lymbery said: "This investigation shows that the battery cage is a system that cannot simply be cleaned up, but one which is, in our view, inherently cruel.
"Battery cages are so small that the hens cannot stretch their wings, and so restricting that the birds' bones become brittle to the point where they can simply snap from under them."
The group's investigation was disclosed initially on BBC One's Here and Now programme.
CIWF hopes the findings will influence a vote in the European Parliament early next year on the future of battery cages.
Campaigners are pushing for an EU-wide ban on the system for egg-laying hens and aim to free the UK's 30 million battery hens.
The group has long lobbied shoppers to buy only free-range eggs.
Compassion In World Farming
MAFF
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