Supermarkets rationing salad and vegetables has led to the emergence of a new "black market", as experts urge shoppers to buy more seasonal British produce.

It comes after the UK's supply of salad and vegetables was decimated by storms across the Med, leaving supermarket shelves empty as they struggled to meet demand.

On Thursday Tesco and Morrisons launched a crackdown to prevent customers from buying more than three Spanish-grown iceberg lettuces at a time in a bid to preserve stock.

But the ban has led to markets and causal sellers taking advantage of desperate salad fans by flogging them salad and vegetables for up to 10 times the usual price.