Norfolk farmers have warned that egg shortages could be the "tip of the iceberg" unless supermarkets pay fairer prices to avoid wider food supply failures.

Many retailers have started rationing the number of eggs being sold to customers.

Farming leaders said soaring production costs - including chicken feed, energy and packaging - have crippled many egg producers, causing farms to reduce hen numbers, pause production, or quit the industry altogether.

Hundreds of thousands of birds have also been culled as a result of the nation's worst bird flu outbreak on record.

But farmers said this is not the reason for the empty shelves, instead blaming the growing gap between the cost of production and the price paid by retailers.

Supermarkets said they valued the long-standing relationships with their suppliers and "know they need to pay a sustainable price to egg farmers" - but they are also dealing with rising costs and needed to limit price increases for hard-pressed consumers.

Norfolk farmer Rebecca Mayhew said the same cost pressures affected many other food sectors, including pork and dairy - but the full effect on them is yet to be seen.

"The issue with the eggs is the tip of the iceberg for agricultural production," she said.

"With chickens, it is a really short cycle. You go from newly-hatched chicks to egg-producing birds in 20 weeks.

"So it takes very little time to go out of egg production, whereas it takes a lot longer to go out of milk or pig production, for example.

"Because there is such a short cycle, six or eight months ago a lot of egg producers looked at the contracts being offered and said: 'I can't make it work, I just won't re-stock the shed'.

"This is why this is the beginning of a huge food crisis. This is the first of many incidents we are going to see across the whole food chain."

Mrs Mayhew has 300 free-range hens at Old Hall Farm at Woodton near Bungay, and sells the eggs direct through her farm shop and online orders.

She said supermarkets were warned about the potential impact of low prices months ago and, while bird flu was a major industry concern, it should not be used "as an excuse" for egg shortages.

Eastern Daily Press: Sam Mitchell with his hens at The Cluckery in Repps With Bastwick, near Great YarmouthSam Mitchell with his hens at The Cluckery in Repps With Bastwick, near Great Yarmouth (Image: Kate Wolstenholme)

Sam Mitchell manages more than 30,000 hens at The Cluckery, part of his family's mixed farm at Repps With Bastwick, near Great Yarmouth.

His flock - which is usually free-range but has been ordered indoors as a precaution against bird flu - produces about 28,000 eggs per day.

He warned six months ago that the industry was in a "dire situation" which would force people out of the industry if prices did not improve - and the current shortages indicate that they have not.

Mr Mitchell said feed costs have gone up £70 per tonne in the last year, electricity prices have more than trebled and the price of pullets (young hens) has risen by £1 each.

Those three factors alone have added 25p to the cost of producing a dozen eggs, he said.

Meanwhile data from the British Free Range Egg Producers Association (BFREPA) shows while the average price of a dozen eggs has risen by about 50p in supermarkets, some farmers have only seen a price rise of between five and 10p.

"It just shows that things have to change," said Mr Mitchell. "The supermarkets need to speak to their producers and we all need to be on board to make sure it is a sustainable industry."

Eastern Daily Press: Sam Mitchell with an egg produced at The Cluckery in Repps With Bastwick, near Great YarmouthSam Mitchell with an egg produced at The Cluckery in Repps With Bastwick, near Great Yarmouth (Image: Archant)

This week, Marks and Spencer and Morrisons became the latest grocers to join Tesco, Asda and Lidl in rationing the sale of eggs.

However Waitrose said it has no plans to introduce such limits, claiming its £2.6m investment in its egg suppliers will go directly to supporting farmers.

Andrew Opie, director of food and sustainability at the British Retail Consortium, the trade association representing supermarkets, said: “While avian flu has disrupted the supply of some egg ranges, retailers are experts at managing supply chains and are working hard to minimise impact on customers.

“Retailers have long-standing, established relationships with their suppliers and know how important maintaining these are for their customers and businesses.

"Supermarkets source the vast majority of their food from the UK and know they need to pay a sustainable price to egg farmers, however, they are also facing additional costs and are working incredibly hard to limit price increases for consumers during a cost-of-living crisis where many people are struggling to afford the essentials.”

In response to the concerns over wider food shortages, he added: "Despite the temporary disruption to the supply of some egg ranges, food supply chains remain strong and retailers remain confident that customers can get all the food and essentials they need for Christmas."

The National Farmers' Union (NFU) has called for the government to launch an "urgent investigation" into the egg supply chain disruption.

The NFU said Defra should look into whether a declaration should be made under the Agriculture Act 2020 to trigger "much-needed support" for producers.

The government said the situation is being monitored but insisted the UK's food supply chain is "resilient" and that no "significant impact" is expected overall.