Shops, brands and companies recall food products when there is a fault with the item. This makes it unsafe to consume as it could cause harm to some people.
The food retailer added: “We apologise for any inconvenience caused.”
The product recall notice was also released on the Food Standards Agency (FSA) website.
The organisation added its own information and guidance to customers on what they should do if they have already purchased the product.
It said: “Co-op is recalling Coop Tuna Mayo Sandwich because the product has been found to contain a foreign body.
“The presence of an unknown foreign body makes this product unsafe to eat.”
The FSA continued: “If you have bought the above product do not eat it.
“Instead, return the product to nearest Co-op store for a refund, or if you are self-isolating or shielding please contact our Customer Careline 0800 0686 727 or email@example.com.”
Co-op issued its product recall yesterday, being the latest supermarket to have a problem with one of its items.
But other UK supermarkets have recalled food products in recent days and weeks.
Earlier this week, Sainsbury’s recalled its Love Your Veg Butternut Squash & Lentil Lasagne because it contains milk which is not mentioned on the label.
This means it is a possible health risk for anyone with an allergy or intolerance to milk or milk constituents.
The product also contains beef and pork, again not stated on the packaging, because it was incorrectly packed with Sainsbury’s Bolognese Melt.
Customers should return the product to their nearest Sainsbury’s store for a full refund, and no receipt is required.