Asda, Sainsbury’s and Tesco are set to improve allergen labelling across their in-store bakeries.

The move follows an investigation by the BBC’s Watchdog programme, which found that staff at some branches of the retailers’ stores had given confusing or incorrect information about allergens when approached by undercover journalists posing as customers with food allergies.

All three supermarkets have now said they are reviewing how allergy information is displayed. Asda and Sainsbury’s both revealed they were working to roll out more detailed allergy information across their in-store bakeries, while Tesco said it was currently reviewing how its information is displayed.

The programme found “cause for concern” at five of the 24 sites where it asked for information about allergen ingredients at the bakery counter.

Under current regulations, there is no obligation for businesses to label allergens on foods prepared on the same premises as they are being sold.

In one Sainsbury’s branch a staff member assured Watchdog’s undercover journalist that its raisin whirls were free of nuts. However, after a delay while the staff member located an in-store ‘product information guide’, the journalist then found that almonds were listed as an ingredient.

“Customer safety is our priority and we are updating our labels to include more specific allergen information,” a Sainsbury’s spokesperson said.

The retailer currently displays notices in its bakeries directing customers to speak to staff who can provide more information on the ingredients and allergen information of products.

Problems were also found with information about allergens at three Asda stores, according to the programme, including one where no information was available. However, Asda insisted that in all instances flagged up by Watchdog its staff advised the customer not to buy the product.

A spokesperson for Asda said it took its responsibilities as a retailer “incredibly seriously” and noted that its in-store bakeries featured “clear signage” on the potential for allergens in products. It added that the bakery products themselves were also labelled to warn of the potential presence of nuts, seeds and other allergens, while its bakery staff were trained to provide allergen information.

“We recognise that in three of the eight mystery shops [investigated] by Watchdog we did not provide the customer with the definitive information they were looking for,” the spokesperson added.

“We are always looking at how we can do a better job for our customers and entirely support Watchdog’s call for more detailed allergen information on packs. We have been working on improvements to the clarity of allergen information on our website and are also working to implement detailed allergen labels on our in-store bakery products.”

Tesco’s policy for loose bakery items is that it displays signs asking customers to speak to staff – who are given “comprehensive training” – to get the relevant allergy information.

However, at a Tesco branch an undercover journalist posing as a milk allergy sufferer filmed a senior staff member who was unable to locate any ingredients information, including allergens, for an unpackaged panini containing milk.

“At present we exceed the current legal requirements by providing allergen information on all products that are packed in-store by our bakers,” said a spokesperson for the retailer.

“In light of the Watchdog investigation at our Droylsden store, we have reminded all staff about the importance of allergens and how to ensure customers are given the correct information. Additional and more prominent signage has also been provided to our stores to encourage customers to speak to staff. We are currently reviewing how allergy information is displayed moving forward and we would be keen to input into any proposed reforms to labelling laws.”

Allergen labelling is under the microscope following the death of a 15-year-old who suffered a fatal allergic reaction to a sandwich from Pret A Manger. The sandwich contained sesame, to which she was allergic. The company has since pledged to list all ingredients, including allergens, on products that are freshly made in its kitchens.

The full report on allergens in supermarkets’ bakery products can be seen on Watchdog Live tonight (7 November) at 8pm on BBC One.