More than $1.1 million cash was found during a vehicle stop in Ballina. Photo / NSW Police

More than $1.6 billion worth of ice has been seized from shipping containers, marking Australia's biggest drug bust, with police labelling the seizures as "staggering".

As part of Strike Force Chellington, Australian Border Force officers examined 24 sea cargo containers that had arrived into Port Botany last month.

They allegedly uncovered 748kg of methylamphetamine - also known as ice - concealed within marble stone.

Three men — aged 24, 26 and 34 — were charged and remain before the courts.

ABF officers then examined 19 more containers that arrived via sea cargo at Port Botany last week.

They allegedly found 1060kg of methylamphetamine concealed in the same marble stone method.

In total, more than 1800kg of ice, which has an estimated street value of more than $1.6b, has been seized during the investigation.

On Friday, Detective Acting Chief Superintendent John Watson said the investigation remained ongoing.

"At this stage no one has been charged in respect of this particular consignment, although they are being considered in relation to the broader investigation," he said.

"The investigation has resulted in 1.8 tonnes of methamphetamine – the biggest in Australia's history.

"To date, our investigation has been focusing onshore, but the AFP are now focusing their efforts overseas with us.

"We will not stop until every line of inquiry in relation to this seizure has been made."

Watson noted the factory that was being used as the final destination point last week was dedicated to dismantling the pallets and removing drugs from the consignments quickly.

"The capability that this syndicate has demonstrated to us, in terms of volume in size, is enormous. These figures are staggering."

Watson said the alleged offenders had international connections, which authorities were looking into.

"We don't know how long they have been operating, but it is certainly a line of inquiry that we are keen to understand.

"The Middle Eastern region is probably our focus, but I certainly wouldn't restrict our investigation to just that region either."

ABF Assistant Commissioner Erin Dale said it did not matter how sophisticated the method of concealment was because officers were highly trained and skilled to uncover such crimes.

"The audacity of these individuals to think they could import such vast quantities of harmful drugs into Australia is astounding," she said.

Separately, NSW Police have charged four people over the alleged importation of more than $155 million worth of drugs.

ABF officers first examined a shipping container consignment at Port Botany from Canada earlier this month.

About 161kg of methylamphetamine and 30kg of cocaine was allegedly found inside a 1960 vintage Bentley S2, with some of the drugs concealed behind the headlights.

Strike Force Chime was established to investigate the importation and executed a search warrant at a home at Rooty Hill, about 3.30pm on Thursday.

The Bentley and a Ford Focus were seized, as well as mobile phones and a computer.

Tools, including an angle grinder, were forensically examined at the scene.

A 23-year-old Rooty Hill man has been charged with seven offences, including importing a commercial quantity of a border-controlled drug, dealing with property proceeds of crime, large commercial drug supply, and participating in a criminal group contributing to criminal activity.

A 22-year-old Botany man has been charged with six offences, including importing a commercial quantity of a border-controlled drug, large commercial drug supply, dealing with property proceeds of crime, and participating in a criminal group contributing to criminal activity.

Both men have been refused bail and will face Mt Druitt Local Court.

During additional inquiries, officers stopped a Toyota Prado on M1 at Ballina about 2.30pm on Thursday.

They allegedly found 2.2kg of methylamphetamine and more than $1.1m in cash hidden beneath the cargo area.

A 25-year-old Homebush West man was charged with eight offences, including importing a commercial quantity of a border-controlled drug, large commercial drug supply, dealing with property proceeds of crime, and participating in a criminal group contributing to criminal activity.

A 25-year-old Plumpton woman was charged with participating in a criminal group contributing to criminal activity and dealing with property proceeds of crime.

Both were refused bail and will appear at Ballina Local Court.

Investigations under Strike Force Chime are also ongoing.