“Misleading” and “inconsistent” labels make it hard for shoppers to know where their food comes from, the consumer champion Which? has said, as it found supermarket chains were selling products with “meaningless” statements on their packaging.

Retailers must supply the “country of origin” for specific foods including fresh fruit and vegetables, unprocessed meats, fish, wine and olive oil but the rules do not generally apply to processed meat or frozen or processed fruit and vegetables.

However, Which? researchers on store visits found that, even when the country of origin was required, it was sometimes missing in store, as was the case with loose cauliflowers, courgettes and onions at Sainsbury’s and peppers, melons and mangoes at Asda.

Two-thirds of people surveyed by Which? said they thought it was important to know where fresh fruit and vegetables came from. Half of respondents said it was also important to know the origin of processed and tinned meat.

Which? also highlighted inconsistencies. A whole own-label pineapple in Tesco carried the country of origin, while a packet of pineapple chunks in the next aisle did not. This is within the rules but not particularly helpful for shoppers, the consumer group said.

In other cases, Which? complained that labels were misleading or, worse still, meaningless. Aldi’s Crestwood bacon and cheese wraps were an example of the former as they showed union jacks and the claim “Made in Britain” on the front of the packet but on the back of the products revealed they contained EU pork.

A pack of gammon joints at Iceland was labelled as “EU and non-EU origin” – a statement that was described as “meaningless”. Analysts counter that this type of label is intended to inform customers that the product contained a blend of an ingredients from different countries, including UK sources.

Ele Clark, the retail editor at Which?, said that, even when the rules were being followed, consumers were not getting all the information they wanted.

“Supermarkets should particularly focus on labelling loose fruit and vegetables more clearly, but manufacturers and retailers should also consider providing origin information on more processed meat products so shoppers are armed with the information they need to make informed choices,” she added.

Which? said it planned to share its findings with Department for Environment, Food and Rural Affairs, which this year announced a consultation on food labelling to improve transparency so consumers can “make informed decisions”.

Separately, post-Brexit government plans will require all meat and dairy products sold in the UK to be labelled “not for EU” from October, which food producers say could add £250m a year to their costs.

Sainsbury’s and Asda said they had stringent processes in place to ensure country of origin is clearly displayed at the shelf edge and on products themselves where applicable. Aldi said it worked hard to ensure that all its labelling complied with the rules.

Andrea Martinez-Inchausti, an assistant director of food at the lobby group the British Retail Consortium, said retailers attempted to ensure they “followed all legal guidelines where country of origin labelling was required. Furthermore, they go above and beyond to voluntarily provide this information in many circumstances where it is not a legal requirement.”