Free-range egg producers are furious that at least one supermarket is planning to import free range eggs from France.

Somerfield has said it plans to source 40% of its free-range needs from northern France because of a shortfall in British supplies. Another retailer is rumoured to be considering a similar move.

But the industry has claimed that supermarkets are to blame for the shortfall because they are paying prices that leave no margin either for new investments or expansion.

NFU president Peter Kendall said he was writing to all of the major retailers, pointing out the free range standards are significantly lower on the continent than in the UK.

EU rules governing French free range production allow a stocking rate of 2500 birds/ha, whereas the Lion standard, to which UK producers work, only permits stocking up to 1000birds/ha.