llicit drug experts suspect 700kg of cocaine seized on a ship docked in Tauranga was destined for another country.

Customs announced the bust yesterday - New Zealand's biggest ever.

It tops another record sting two weeks ago, when 613kg of methamphetamine was found at Auckland Airport.

The cocaine arrived in packages in a shipping container that left South America in January.

Customs estimates it has a potential street value of $280 million.

Investigations manager Cam Moore says it's "extremely significant" and highlighted how organised crime groups are trying to "exploit" NZ for international drug smuggling.

He told RNZ "the use of borders and access through shipping routes is internationally a global trend, it's not just specific to New Zealand".

Massey University illegal drug researcher and associate professor Chris Wilkins says the cocaine packages would have well-exceeded demand.

"Cocaine use in New Zealand is really a boutique kind of market, most likely due to its high price. It's in kind of an affluent group, and it's not very widely used."

So he suspects the packages were meant to go across the ditch.

"In Australia, there's a much bigger market and drug smuggling organisations often use transit countries like New Zealand or some of the Pacific Islands to put drugs into Australia."

Drug Foundation executive director Sarah Helm says normally only 700g of cocaine is used across the country weekly - the shipment was 1000 times that.

"We're not even convinced that there would be a market for that amount in New Zealand, that it would so big. And maybe the intention was to ship that product on."

Helm also says busts are only part of the picture.

"Often times when we seize a bit of product or we clamp down on one supplier, someone else will pop up in their place, because we haven't reduced demand."

She says addiction programmes like Te Ara Oranga in Te Tai Tokerau, which police reported reduced participants' drug harm by 34 per cent, needed to be rolled out nationally, to slim the market for illicit drugs in Aotearoa.

-RNZ/Sam Olley.