The device was found by a member of the public at Pontac on Wednesday morning.
The Islander moved the device up the beach, and the States police are now urging people to ensure they don’t pick up suspect objects.
In a Facebook post, the force said: ‘The bomb disposal officer attended and carried out a controlled explosion, disposing of the mortar shell safely.
‘However the device was moved before we arrived and although done with good intention we would like to remind the public that should you ever come across any such device, please DON’T touch it and call us straight away.
‘The mortar shell found this morning was a live device and could have resulted in a very different situation.’
