Some types of bread products are being taken off the shelves in Iceland and other supermarkets could follow suit.
'The Real Bread Campaign' is against 'half and half' loaves and has claimed a large outlet has already taken the product off sale.
Campaigners say Iceland has removed its own-brand ‘50% white and wholemeal’ loaf after a complaint was made by the lobby group to a trading standards
The Liverpool Echo reports Iceland is among five companies contacted in June 2022 about the naming of ‘half and half’ products.
It is asking them to review the marketing saying by law the word wholemeal ''can only be used in a product name or marketing if all of the flour in that product is wholemeal''.
It is continuing to follow up its complaint about Hovis, Jacksons and Warburtons.
And also made official complaints to Bolton Metropolitan Borough Council, Buckinghamshire & Surrey County Councils, Hull City Council and London Borough of Waltham Forest.
The group says one authority is now referring the complaint to the Department for Environment Food and Rural Affairs (Defra).
Chris Young, coordinator of the Real Bread Campaign said: “The law is clear on what you can and can’t name and market using the word wholemeal.
''It’s good to see Iceland’s move in line with this, though they could’ve just renamed the product.
"The problem here is that the law and official guidance clearly state that the word wholemeal can only be used in a product name or marketing if all of the flour in that product is wholemeal.
''While we're working hard to convince the government to improve loaf labelling and marketing legislation in the UK, it's a worry if manufacturers and retailers can't even follow the law as it stands.
"Evidently there’s an issue with the content, understanding and enforcement of current legislation, a full overhaul of which is long overdue.
"Bakers helping people to trade up from 100% white to at least fifty-fifty is a good thing.
"What we don't want to see from industrial loaf fabricators is any marketing that's misleading or otherwise breaches applicable regulations.
''While they're at it, we'd love to see them ditching the additives they use, all of which are unnecessary by definition."
Campaigners will continue to lobby government to review the regulation of 'wholegrain' and 'wholemeal' as part of its wider Honest Crust Act work.
The five loaves the campaign has targeted are Hovis: Best of Both, Iceland: 50% White and Wholemeal, Jacksons: Bloomin' Both, Warburtons: Half White Half Wholemeal.
The Bread Campaign said: ''having received unsatisfactory responses from two of the companies, and no response at all from the other three, we emailed the trading standards department of LB Tower Hamlets, the local authority for where the Real Bread Campaign is based''.
Campaigners say the legal manager at Buckinghamshire & Surrey Trading Standards has said it is referring the matter to Defra.
It wrote: “Having looked at the legislation I have come to the conclusion that it would help achieve greater clarity if we referred the matter to the central government department responsible for the legislation.
'As the product is not the only one of this type on the market we think it is important to have a definitive view from central government so that coordinated advice can be given.
"This service has contacted Defra with the relevant details and asked them for their opinion about how the Regulations would apply to products such as the one in question.
''Once we have received the opinion from Defra we will review our advice and contact you to inform you what the result is.”
Chris Young added: “The existing, outdated Bread and Flour Regulations are no longer fit for purpose, if indeed they ever were.
"A full review and overhaul is long overdue but the government continues to resist our Honest Crust Act proposals for up-to-date composition, marketing and labelling legislation.”
