Eggs laid by hens kept indoors for months straight due to bird flu could be sold as free-range under a potential relaxing of rules.

It comes as egg farmers in the UK have been battling the biggest avian flu outbreak on record, leading to fears of shortages.

Under changes being looked at by ministers, there could be a relaxation of how free-range is defined, meaning hens kept in barns for long periods could meet the new criteria.

As it stands, if a bird is housed indoors for more than 16 weeks it cannot be defined as free-range.

The department for environment, food and rural affairs (Defra) is considering the changes to help UK farmers compete against their counterparts in Europe, Whitehall sources told the Daily Telegraph.

Retailers and hospitality firms have been forced to switch up their supply chains this year in order to cope with the outbreak.

Some 3.8m birds have died as a result of the avian flu outbreak, according to official data published last month, with fears the flu could spread further this winter.

Egg farming representatives have said it is critical for UK businesses that the country is on par with the EU.

Robert Gooch, chief executive of the British Free Range Egg Producers Association, has said previously: “It’s very necessary that the UK aligns with the EU, otherwise retailers will import eggs labelled as free range from housed hens in the EU in the event of an AI epidemic when there are none on the UK market.”

Rules in place in England and Wales currently mean birds must be housed to protect them from bird flu and stop the spread of the disease.

Egg producers have seen their production costs shoot up over the past year, with businesses previously calling on supermarkets to hike prices and pass on the increase to producers.

Feeding hens has become at least 50 per cent more expensive over the past year while fuel spending has increased 30 per cent, according to the British Free Range Egg Producers Association.

NFU poultry board chair James Mottershead said: “The British poultry sector has experienced an unprecedented year with record levels of avian influenza (AI), which is devastating family farm businesses across the country.

“We have seen how stringent biosecurity measures can help reduce the risk of AI and we urge all bird keepers to remain vigilant, whether you are a professional poultry farmer or someone who keeps a small number of hens in their garden.”