Sainsbury's has been advised that the oversleeve used on its 'colin' pollack product went against food labelling regulations.

The supermarket launched the limited promotion to highlight awareness of the underused species, but was investigated by the Environmental Services Department at the City of London Corporation after a consumer complaint.

The department concluded that the oversleeve went against the various legislation governing the labelling of food in general, and fish in particular. It has issued advice to Sainsbury's over the need on the outer packaging for essential information on the name of the food, its eat-by date and the name of the manufacturer, packer or seller.

Sainsbury's had since given assurances that all future promotions would be fully compliant with the law, said a City of London Corporation spokesman.