VEGETARIAN products sold in supermarkets frequently contain eggs from hens kept in battery cages claims a report.

The news has angered animal rights activists who have bought vegetarian produce under the belief that ingredients and methods used would not involve cruelty to animals.

RSPCA experts who compiled the report said nine of the 11 retailers questioned by the charity, including Tesco and Asda admitted using battery eggs in products labelled as suitable for vegetarians.

According to an RSPCA spokesperson, such supermarkets were failing to consider vegetarian consumers not wishing to eat food products derived from cruel farming practices.

John Avizenius, senior scientific officer for the animal welfare charity, said: "The news that supermarket own-brand vegetarian products contain eggs from battery systems will shock many vegetarian consumers but, on top of this, the absence of clear food labelling means some supermarkets are denying their consumers a right to choose."

However, he said consumers could be comforted by the presence of Marks & Spencer, which used only free-range eggs in its own-brand vegetarian food and, along with the Co-op, clearly labels all its products.