Food exports face being turned away from the EU if there is a no-deal Brexit – because the government told firms to attach the wrong proof that they are fit to eat.

Producers have condemned the “confusion and chaos” surrounding compulsory health and identification marks after official advice was changed just weeks before departure day.

It means food products of animal origin (POAO) are likely to be rejected by the EU if they are stamped ‘UK’, rather than ‘GB’ or ‘United Kingdom’.

The bar will be imposed if the UK crashes out of the EU without a deal, on either 12 April or 22 May – the new danger dates imposed by the EU – but could also be a requirement even if Theresa May’s deal, with a 21-month transition period, is eventually passed.

Ian Wright, chief executive of the Food and Drink Federation, said: “This is going to cause confusion and chaos both for producers and shoppers.

“At very late notice, we must make a change that will cost businesses a huge amount of money and that we may not be able to sort out in the time available.”

Mr Wright also warned that, even if packaging can be changed, much of it was simply too small to carry the description “United Kingdom”.

Tariffs in the event of a no-deal Brexit Show all 15 1 /15 Tariffs in the event of a no-deal Brexit Tariffs in the event of a no-deal Brexit Pork There will be tariffs on pork in order to protect British farmers Getty Tariffs in the event of a no-deal Brexit Cheese There will be tariffs in place on some cheeses including €22.10/100kg of cheddar, €19.10/100kg of processed cheese and €18.60/100kg on some blue cheeses Getty Tariffs in the event of a no-deal Brexit Milk There will be no tariffs in place on milk Getty Tariffs in the event of a no-deal Brexit Car Parts There will be no tariffs on car parts imported from Europe PA Tariffs in the event of a no-deal Brexit Cars However finished cars will face tariffs of 10.6% Getty Tariffs in the event of a no-deal Brexit Alcoholic drinks There will be no tariffs on alcoholic drinks - except on some rums due to ingredients used in their distilling process Getty Tariffs in the event of a no-deal Brexit Beef There will be tariffs on beef in order to protect British farmers Getty Tariffs in the event of a no-deal Brexit Fish There will be no tariffs on many types of fish including cod, haddock, salmon and sea bass Getty Tariffs in the event of a no-deal Brexit Fruit and vegetables There will be no tariffs on almost all fruit and vegetables Getty Tariffs in the event of a no-deal Brexit Chocolate There will be no tariffs on chocolate or other cocoa products Getty Tariffs in the event of a no-deal Brexit Poultry There will be tariffs on poultry in order to protect British farmers Getty Tariffs in the event of a no-deal Brexit Ceramics There will be some tariffs in place on ceramis Getty Tariffs in the event of a no-deal Brexit Steel There will be no tariffs on steel Getty Tariffs in the event of a no-deal Brexit Coal There will be no tariffs on coal Getty Tariffs in the event of a no-deal Brexit Lamb/Mutton There will be tariffs on the meat of sheep in order to protect British farmers Getty

“Furthermore, GB is not a recognised description of a country of origin and may have ramifications for producers in Northern Ireland,” he added.

The fears were echoed by the British Poultry Council, which warned of “multiple consequences” from not having the UK mark, or a single mark.

“We don’t know where products are going to be exported – and if there are consolidated products from several slaughter houses, with different marks, there could be problems at border inspections,” said Shraddha Kaul, its public affairs manager.

The problem has blown up because, after the UK leaves the EU, products cannot carry the ‘EC’ mark as proof of production in an approved establishment and fit for human consumption.

Last year, producers were told to prepare with packaging stamped ‘UK’ – but the European Commission then ruled that would not be acceptable.

The Food Standards Agency (FSA) only changed its advice in mid-February, in instructions sent to thousands of firms making meat, egg and milk products.

It reads: “For businesses who export POAO to the EU, the health and ID marks must carry either: the official two-digit ISO Code GB or the full country name in capital letters UNITED KINGDOM.”

If there a crash-out Brexit, “the revised marks would apply to all POAO exported to the EU immediately from the date of the UK’s exit from the EU (29 March 2019)”. That date has now been revised.

The FSA also said it could only “aim to agree a transition period”, adding: “The point at which the new marks will come into effect will depend on the nature of the UK’s exit from the EU.”

Mr Wright added: “If producers trading with the EU don’t have the appropriate health mark, those products may have to come back to the UK and be sold at a loss, or they may end up as food waste.

“The advice came less than 6 weeks before it was potentially coming into effect – but the turnaround time for packaging is three months.”

To add to the potential confusion, exports to non-EU countries must be stamped ‘UK’, unless the receiving country has agreed to the new descriptions.

Within the UK, however, an emergency regulation rushed through would allow continued use of the ‘EC’ identification mark until the end of transition, in December 2020.

An FSA spokesperson said: “Following discussions with the European Commission it was indicated that UK proposals would not meet EU third-country legal requirements.