The sack of potatoes contained a nasty surprise

Olga Mauriello, from a small town near Naples, had put the potatoes into water to peel them when she discovered the mud-covered, pine cone-shaped grenade.

She alerted the neighbours, who in turn called the police.

Officers detonated the grenade on Wednesday in a park in the town of San Giorgio Cremano. It is thought to have come from a farm in France.

The grenade had no safety pin and was still active. It is believed to be a type used by the US Army in Europe during World War II.

"If I hadn't felt its weight, I wouldn't even have realised that it was a bomb," she told Reuters news agency.