The Co-op grocery chain is recalling 165,000 hollow milk chocolate Santa figures from across the country after someone allegedly inserted two small batteries into them.

If swallowed, the small, button-shaped lithium batteries can be potentially deadly.

The store confirmed an investigation has established the batteries were deliberately placed inside the hollow treats in at least two separate cases, however it is still not clear who was behind it.

Two customers have so far discovered batteries in their Santas. Both said they broke the chocolate to find the battery inside, suggesting the battery was put inside the chocolate before the hollow cavity was sealed.

But as the chocolate Santas are supposed to be subjected to a metal detector before they leave the factory, the Co-op said how and when the tampering occurred is still unknown.

The Co-op are working with the relevant authorities to determine how the tampering happened. 

A Co-op spokesman said: “The health and safety of our customers is our top priority. We are concerned about two separate instances of alleged product tampering involving our hollow milk chocolate Santa foil figures, which have been found to contain a small battery inside.

“As a result we have begun a UK-wide product recall. The police and Food Standards Agency are being notified. Customers with one of these products should not eat it but call our customer relations team for a full refund.”

The chocolates that had been subject to tampering were bought at two different locations, one in Suffolk and one in Essex but exact locations are unknown at this time.

A spokesperson for West Midlands Police, where the crime was reported, said: "We have been made aware of the reports and we are supporting the Co-op while they investigate to establish what has happened and if there was any malicious intent."

Anyone who is concerned should call Freephone 0800 0686 727. 

No other products are affected.