Free-range eggs have returned to shelves after British farmers were forced to keep all chickens indoors because of a major bird flu outbreak.

It is now possible to purchase eggs from chickens that have been given unlimited access to roam outdoors following a relaxation of measures brought in to control what Government described as the largest ever outbreak of avian flu in the UK.

Free-range eggs have been unavailable to buy since 21 March, as a result of rules introduced in November obliging farmers to keep birds reared for produce of meat indoors to prevent the spread.

Tesco, Sainsbury’s and Asda have all listed free-range eggs on their websites again after the Department for Environment, Food and Rural Affairs lifted the indoor housing rules.

Officials said that other measures including enhanced cleaning must stay in place to protect flocks, and stressed the importance of “scrupulous biosecurity”.