It is famous for its budget offers and rock-bottom prices but when the Lidl supermarket chain received several batches of high-grade cocaine at its Spanish stores last weekend it decided that that was one product which would not be making it on to the shelves.

Instead the budget supermarket group called in the police to solve the mystery of how a dozen of its stores had each received hundreds of thousands of euros worth of neatly wrapped cocaine mixed in with their fresh bananas.

The drugs were discovered at the bottom of banana boxes that went to stores in Madrid, Plasencia and the town of Cáceres. The bananas, which had been imported by sea from Ecuador, arrived at the Mercamadrid wholesale fruit and vegetable market in Madrid last week. There they were snapped up by buyers from Lidl and the Alcampo supermarket group.