Consumers in Aichi Prefecture have been warned not to buy Coco Ichibanya brand beef cutlets after it emerged that some 5,000 pieces due for disposal were instead illegally sold to two supermarkets.

Ichibanya, which operates Curry House Coco Ichibanya restaurants, said Wednesday that it had asked local waste disposal firm Daiko to dump 40,000 frozen cutlets after it was learned that one might contain a piece of plastic up to 8 mm long.

The cutlets were manufactured last September and given to Inazawa-based Daiko in October.

The Gifu Prefectural Government said Daiko asked noodle manufacturing firm Minori Fuzu, in the city of Hashima, to sell some of the cutlets to individuals and two supermarkets in the prefecture.

Some 5,405 are said to have been sold to the supermarkets, which have been identified only as being located in the city of Tsushima and in Nagoya.

When the prefectural officials inspected the noodle manufacturer, they found 800 empty cardboard boxes with the name Ichibanya.

Separately, a Coco Ichibanya worker noticed this week that some of the firm's beef cutlets, normally used only as toppings in the restaurant's dishes, were being sold at one of the supermarkets.

Ichibanya had contracted Daiko to dispose of its waste since 2001. Daiko officials declined comment.