A Sainsbury's children’s yoghurt has been withdrawn over fears it may contain pieces of blue plastic.
The supermarket giant told consumers it was a "precautionary measure" but urged customers to return Strawberry Fromage Frais Pouches to a branch where they will receive a full refund.
It confirmed the product is "a possible risk to health".
The Food Standards Agency said a small puck-shaped disc may have made its way into one of the pots.
A spokesman for Müller said, "This is an isolated incident and an extensive investigation by Muller Yogurt & Desserts quality team is under way."
The pink disc, measuring 3cm by 1cm, is used on the production line, the company added.
The affected batch will be a four-pack of 135g servings with a best before date of 27 April 2016.
The food watchdog urged consumers to get in touch, saying, "If you have bought the product listed above, please do not eat it.
"Instead contact Müller Yogurt and Desserts at email@example.com."