Drugs with an estimated value of more than £600,000 have been found inside a box of bananas by a Tesco worker.

The worker was unpacking the fruit shipped from South America when he discovered five bags, each containing white powder and weighing 1kg, the Mirror said.

Police are investigating after being called to the Tesco superstore in Wokingham, Berkshire, last Wednesday.

Director of drug research company the Independent Monitoring Unit, Matthew Atha said: "White powder from South America? It's going to be cocaine."

Mr Atha said each bag could be worth up to £150,000 and even more when valued at street value.

Tesco say on their website that the majority of their bananas are imported from farms across Costa Rica and then transported to "distribution centres" throughout the UK before being sent out to stores.

Mr Atha said it was possible someone from the distribution centre missed the collection of the drugs.

He said: "I think that it is not impossible that someone in Tesco was involved in it, but it is more likely that it is someone from the distribution who wasn't there on the day to collect the delivery, or had been arrested on other charges."

Thames Valley Police said: "We were called on 22 July to Tesco at Finchampstead Road, Wokingham to reports of packages being found in a consignment of fruit. They are believed to be class A drugs. Officers are investigating."

Mr Atha added: "It is quite likely that it has been going on for quite some time. The authorities will be paying particular attention to whoever the distributor is I expect."

In two recent similar discoveries £11m worth of cocaine was accidentally delivered in boxes of fruit to 13 German branches of supermarket Aldi and in 2013 the class A drugs were found again in bananas in a Danish store.

A Tesco spokeswoman said: "We are helping police with their investigations."