A criminal investigation has begun into “alleged product tampering” following the latest incident affecting the Co-operative which the Food Standards Agency warned could cause choking and burns.

The convenience-store giant has recalled its £1 hollow milk chocolate Easter bunny foil figures after a small battery was found inside one of them in Nottingham.

The Co-op said it had sold more than 3,000 units of the bunnies across the UK.

The National Crime Agency is advising Nottinghamshire Police and the Food Standards Agency has been informed.

The Co-op has displayed point of sale notices in stores where the product was sold. It said the health and safety of its customers was uppermost in its mind.

“We are concerned about one incident of alleged product tampering involving our hollow milk chocolate Easter bunny foil figure, which has been found to contain a small battery inside,” a spokesman said.

“This follows an incident at Christmas when two similar products were targeted and contaminated. As a precaution, we have begun a UK-wide product recall and have withdrawn the product from sale.”

The products targeted at Christmas were Chocolate Santas from the same manufacturer as the latest incident, WAWi.

C-Store understands the Co-op is confident the problem does not stem from the manufacturer and is satisfied with the checks made throughout the supply chain.

But it acknowledged that someone had maliciously tampered with products with the aim of causing harm.

“We can’t say how that’s happened and the enquiries are ongoing,” the spokesman said.

The Co-op urged customers with one of the chocolate bunnies not to eat it but take the product back to store for a full refund.