MPs have accused the Government of a “fundamental breach of sovereignty” over post-Brexit EU labelling rules. A whole raft of new food products sold in Northern Ireland will have to carry “not for EU” labels from July 1.

The labels are controversial for businesses, who claim they are not only off-putting to consumers but costly for manufacturers and food exporters. Reform’s deputy leader Richard Tice said: “This is a bad faith move from the European Union. UK-made goods are of the highest quality and remain in strong demand across Europe.

“We left the EU to restore our sovereignty and forge competitive trade deals on our own terms. Unfortunately, the EU deal showed that this Government is too often willing to compromise British sovereignty to appease foreign interests.”

The rules, set out in the Windsor Framework deal between the UK and EU, are supposed to ensure that goods are not moved onward from Northern Ireland to the Republic of Ireland, an EU member country.

Former Tory MP Sir John Redwood said: “Save our sovereignty. Today, the Government wants to put GB under EU food laws. MPs should oppose this new regulation, which the Government does not want to highlight. The Marking of Retail Goods Regulations being smuggled through Parliament today is another way to bind us to EU laws and prevent Brexit wins.”

Campaign group Facts 4 EU warned the changes mean that a food manufacturer in Birmingham supplying customers anywhere in England, Scotland and Wales must have new packaging saying “not for EU” on their products.

This would apply even if the firms never sell to Northern Ireland, the group added.

Jim Allister, Traditional Unionist Voice MP, said: "GB businesses will have to play by EU rules to trade within their own country. That’s a fundamental breach of sovereignty."

The latest rollout will cover some fruit and vegetables, fish and composite products such as pizzas and quiches. Meat and dairy products sold in Northern Ireland already carry the labels.

The requirement was originally set to apply UK-wide, but that plan was scrapped last year following a backlash from businesses – with the caveat that they could be reimposed if supplies to Northern Ireland are detrimentally affected.

Fact 4 EU’s Leigh Evans, chairman of the Stand for Our Sovereignty campaign, said: “For some time it’s been clear to us all at the Stand for Our Sovereignty campaign that the sovereignty of the United Kingdom – hard won and deeply cherished – is under threat as never before.”

A Cabinet Office spokesperson confirmed to Politico that the need for the labels would likely be “diminished” because of any sanitary and phytosanitary (SPS) agreement.

Under the terms of the deal agreed by Sir Keir Starmer, Britain is preparing to sign up to European single market regulation on animal and plant health, known as SPS rules, removing the need for the labelling.

“In the meantime, it is important to implement the existing arrangements for the Windsor Framework and we will continue to work closely with businesses across the United Kingdom to support them in implementing these arrangements,” said the spokesman.