Police in Uitenhage say the three mortars found in the Strelizia dam this past week are not from South African.
Spokesperson Captain Gerda Swart also confirmed that the mortars were very old.
Police have warned the community not to pick up or handle any strange or foreign objects that they recover at the Strelitzia dam at the town.
On Friday two people found two old and unused mortars in the dam, and transported them, not realising that they could have had fatal effects.
Swart says it was later discovered that the two mortars were, in fact, still live and could have detonated.
The Bomb Disposal Unit from Port Elizabeth was informed and the mortars were deactivated.
She says on Saturday, a man was fishing at the same dam and a third live mortar was discovered.
The man notified the police and the Bomb Disposal Unit was immediately summoned to the scene and members took possession of it.
Swart says the dam's level dropped over the last few months and it is believed that this could be the reason for the recent discoveries.
Police are urging the public to contact the police should they stumble upon anything strange or anything that resembles a mortar, and not to handle or pick it up.
Captain Swart says the Bomb Disposal Unit has not found any other mortars.