The Australian Federal Police said the seizure of more than 400 kilograms of drugs from SA waters would likely lead to "payback" in the criminal underworld, and is warning of further arrests.
The AFP yesterday revealed details about the bust, alleging the Cyprus-registered cargo vessel the Kypros Bravery had been used to transport the drugs which were then dropped in "deep waters" several nautical miles off Yorke Peninsula on March 15.
Four Filipino crew members — Alcris Dente Mabini, Mark Torrenueva Enriquez, Angelito Devalque Balansag and Ian Gelan Dizon — were charged with drug importation and today appeared in the Port Adelaide Magistrates Court.
The men did not apply for bail and will face court again later this month.
Police yesterday said the 416-kilogram shipment was "destined for all major cities in the country" and is the largest amount of cocaine ever detected in South Australia, with a street value upwards of $250 million.
"This represents, according to last year's data, just under half the total of cocaine seized in Australia — this is significant," AFP Assistant Commissioner Peter Harvey said.
"[The operation] resulted in the arrests of at least four — there may be more, and they may not necessarily be involved with the ship itself, but responsible for the business side.
"We're talking about serious crime entities here, and the people involved were senior members of the vessel, at least two of them."
Volunteer coast guard members confirmed they had rescued a small boat that had run out of fuel in Investigator Strait, near Kangaroo Island, on the same day the cocaine was seized.
Police believe the drugs were destined for a predetermined location, and said Australian Border Force were on scene to intercept the drop.
"We'd been focused on the last bit of this operation since the middle of March," Assistant Commissioner Harvey told ABC Radio Adelaide this morning.
"We weren't there by accident."
Assistant Commissioner Harvey said it was common practice for global drug trafficking networks to rely on airports and container ships, but that distribution had evolved in response to the pandemic.
"COVID's stopped some of that passenger movement of course so the criminal networks just modify and move, they're very fluid, they are a business and this is a business model," he said.
"Across Australia, we're very high users of cocaine per capita and some of that's because we're willing in this country to pay high prices.
"It's all the mystique and rubbish about drugs being the thing to do in some circles."
Police were reluctant for the time being on further details about how the drugs were dropped overboard, and whether they were sunk or floating on the surface.
Assistant Commissioner Harvey said the Kypros Bravery had since been allowed to resume its cargo operations after being berthed at Port Adelaide, as police questioned each member of the crew of less than 20 people.
"We no longer have any use for that vessel at this point and four of the crew members stay here in this state," he said.
"The vessel at this point is free to leave once all the documentation is signed off, that doesn't mean there won't be further follow-up with crew or owners or others … it's a grain ship, it's fully laden."