Commander Del McKnight said it was probable workers would find more devices during dredging operations ahead of the arrival of HMS Queen Elizabeth next summer.
It comes after an unexploded German bomb was found in Portsmouth Harbour this morning and later detonated out at sea.
Shoppers and residents living in Gunwharf Quays and Old Portsmouth had to be evacuated this afternoon while the operation was being carried out.
Speaking to The News shortly before the bomb was detonated Commander McKnight, commanding officer of the Royal Navy’s Fleet Diving Squadron, said he expected another device to be found before next summer.
He said: ‘I suspect it won’t be the last, there are quite a lot more dredging operations to go before HMS Queen Elizabeth’s arrival in the middle of 2017.
‘We will stand ready to be called out again.’
Two other devices were found in the harbour in September, but today’s device meant a larger area than before had to be evacuated.
Commander McKnight said this was because the other two devices had been kept in the water throughout - which would have a dampening effect on any explosion - while today’s one had been recovered on to the deck of a barge.
He said: ‘Clearly the bomb has been underwater and on the seabed for many years. It’s not a problem while it’s down there but clearly once you start moving it, disturbing it, lifting it out of the water - it could be activated.
‘Clearly [the evacuation] is necessary. We wouldn’t do this sort of thing lightly, so therefore we really do the best thing in order to keep the public safe.‘