A 33-year-old man is expected to appear in court tomorrow after he was charged over the discovery of explosives in the state's South-West.

Bunbury man Ben Roberts is facing five counts of making or possessing explosives in suspicious circumstances.

Last week two packages were found in the Leschenault Estuary containing the explosive substance TATP, which has been widely used in terror attacks, including the London bombings.

Police were forced to detonate the first package at Gloucester Park in Perth after initially mistaking it for drugs.

The Australian Defence Force later detonated the second package at the estuary.

A third package was found on Friday at a disused caravan park at Peppermint Grove Beach near Capel.

Police did not need to detonate the package and it is not known what it contained.

Mr Roberts has been remanded in custody and will appear in the Bunbury Magistrates Court tomorrow.