Officials in environmental health jobs with Redbridge Council have become involved in a case in which a woman said she found mouse droppings in her cereal.
Dee Blake, from Snaresbrook, said she discovered the droppings in a packet of Co-operative brand muesli she bought from a Somerfield store.
She told the Ilford Recorder that the food had a strange smell when she opened the box and her worst fears were confirmed when she poured out a bowl of cereal.
"The cereal was well within its use by date and the box looked fine. But it is despicable. I brought it into my home and could have eaten it," she said.
A spokesman for Redbridge Council said the matter is now being looked into by its environmental health service.
Somerfield, which is owned by the Co-operative Group, has said it is taking the complaint "very seriously" and has asked Ms Blake to return the product to them so tests can be carried out.
Earlier this year, Tesco was fined £17,000 after an investigation by environmental health officers revealed evidence of rodents at its Martlesham Heath store in Suffolk.
