Customs and police were happy to talk about some of the details of New Zealand largest ever cocaine bust in Tauranga today, but not all questions were answered at the police and customs press conference this afternoon.

The 46kg of cocaine with an estimated value of $20 million was hidden in what is believed to be the sea chest near the rudder of the Maersk Antares, a container ship at the port of Tauranga.

The cocaine was picked up earlier today, says Customs intelligence, investigations & enforcement manager Jamie Bamford.

The hiding place is believed to be in or near the sea chest, the intake reservoir from which piping systems draw raw water. Most sea chests are protected by removable gratings, and contain baffle plates to dampen the effects of vessel speed or sea state. On a ship the size of the Maersk Antares, it can be several square metres in area.

When asked if they were arrested upon returning their boat to the ramp, police assistant commissioner investigations Richard Chambers would not confirm – except to say the four men (two Australians, a Croatian and a Serbian) were caught red-handed.

He would not say if the accused smugglers brought their own boat.

'We can't got into that sort of details.

'Obviously the matter is before the court, but criminals of this type will find a number of ways to facilitate their business. That forms part of our investigation and in due course further facts will come out.”

The four arrested men face serious charges and will be out of circulation for a long time, says Richard.

Importing a class A drug carries a maximum life sentence.

The four men are part of what police and customs are calling a ‘trans-national syndicate'. None of them are South American.

They are in New Zealand as visitors and were living in Auckland – where search warrants executed today discovered another 5kg of cocaine a kilogram of methamphetamine and a ‘significant' amount of cash.

The Maersk line's direct connections from South American ports to New Zealand has been operating for a year, but both men were reluctant to confirm if there have been previous shipments.

'The ship itself has come from Columbia. Peru and Chile,” says Jamie. 'We know that is a route exploited by some significant cartels that operate in the Americas.”

New Zealand Customs and police have, with other international agencies, been monitoring trends in drug cartels that smuggle narcotics across the world.

'We take particular interest in networks and understanding networks,” says Jamie.

Last year customs seized 35kg of cocaine.

'We pay one of the highest prices, so we are an attractive market. It's all about greed,” says Jamie. 'Those syndicates and cartels making money off people's misery feel they can come to New Zealand - and as Richard said we will try and stop that from occurring.”

No weapons have been found. Richard says the arrests were carried out with the assistance of police officers from Auckland and Tauranga, along with Customs and intelligence staff.

When asked if the police armed offenders squad took part, he says ‘we always take the necessary safety measures to protect not only police and customs staff but also members of the community'.

'This is a high risk business, so we are not about to make any compromise on safety.”

Ongoing investigations will be taking place into how the cocaine was going to be distributed around New Zealand and who might be involved in that.