Tesco has launched an inquiry after an elderly shopper was bitten on the wrist by an exotic spider in a bunch of bananas.

Ena Woodthorpe, 83, was horrified to discover the creature after buying the fruit at a store in Ryde on the Isle of Wight.

The spider was sent to the Natural History Museum in London, where experts identified it as a Steatoda Nobilis, commonly known as a false widow.

The false widow looks like its deadly black namesake, but has a bite no more venomous than that of a wasp.

Some US producers use natural predators on crops

The supermarket chain was last year dogged by a shipment of Californian grapes carrying black widows.

In separate incidents, three women discovered the spiders, two of which were alive.

Stephanie Thorneycroft, from Wimborne in Dorset, found a black widow, which has distinctive red markings on the underside of its abdomen, climbing up the side of a colander as she was rinsing grapes in her sink.

Tesco said US producers used natural predators to protect fruit, as an alternative to chemicals.

But it strongly denied the distinctive spider, whose venom is 15 times more potent than a rattlesnake, was deliberately used on suppliers' crops in the US.

Spokesman Jonathan Church said: "The idea is to reduce pesticide use by introducing natural predators instead, but we do not use black widow spiders.

"It is possible that is why the spiders in these three cases have got through because if we had used pesticides they would be dead."