The drugs – 95 kilograms in total – were delivered to a number of stores in cities across the western German state of North-Rhine Westphalia, police said.

The supermarket chain in question has not been named. Germany has a number of well-known discount supermarket brands.

The tightly-packaged bricks were first discovered by workers at two stores in Mönchengladbach, and then later that day in the nearby cities of Duisburg, Krefeld, Viersen, Heinsberg and Neuss.

Mönchengladbach police insightfully said: “The investigators are working on the assumption that the food discounter was not the correct recipient for the delivery, but received the goods in error.”