Anyone who has bought the sandwiches recently is urged not to eat them as they may be harmful.
A full refund is available to customers who return them or call the customer service line.
The recall was issued yesterday and applies to all sandwiches with this filling.
A Food Standards Agency spokeswoman said: “Co-op is recalling the above product due to the possible presence of metal.
“Point of sale notices will be displayed in retail stores that are selling this product.
“These notices explain to customers why the product is being recalled and tell them what to do if they have bought the product.”
The Co-op has placed these notices in stores across the country and issued an apology to customers for any inconvenience.