A man involved in a foiled bid to smuggle $1 billion worth of cocaine into Australia has pleaded guilty on the first day of his trial.

Paul Anthony Masterson admitted in the Western Australian District Court today to possessing the illicit drug with intent to sell or supply it.

Police seized what they said at the time was an Australian record 2.4 tonne cocaine haul bound for Australia in November 2022 off the South American coast.

But the drug traffickers had no idea the shipment, which was linked to a Mexican cartel, had been impounded, and the Australian arm of the smuggling syndicate continued to prepare to receive it.

Officers later duped the group into believing the cargo had arrived off the WA coast, with dummy packaging containing an inert substance dropped about 40 nautical miles off the Perth coast.

Over three days in December 2022, a shore party made multiple trips out to sea to retrieve the cargo because they couldn’t find it.

Officers watched their moves from the air and a tactical response group arrested three people aboard a vessel with about 1.2 tonnes of the inert substance.

Detectives raided properties and executed search warrants across WA over the following weeks, with a total of 12 people charged.

Two were charged after police stopped a vehicle on the Great Eastern Highway, near Coolgardie, in January 2023 and found more than $2 million cash inside it.

Masterson’s trial was vacated and he will be sentenced on Friday.