An alleged "inside man" at Tauranga's port has been arrested as part of what police say is a plot to smuggle hundreds of kilograms of cocaine and methamphetamine from Mexico into New Zealand.

Eight members of the alleged syndicate were last week charged with various drug offences after an eight-month covert investigation by the National Organised Crime Group and Customs investigators.

Police believe the men behind the alleged scheme were attempting to purchase the drugs from a Mexican cartel.

One of those arrested worked as a stevedore at the Port of Tauranga, where he had access to shipping containers. Maurice Oliver Swinton, 42, has been charged with conspiring to import a Class A drug into New Zealand. Swinton is yet to enter a plea, but the allegations are unproven.

Hundreds of kilograms of cocaine were to be concealed inside shipping containers, according to police. They say their investigation, Operation Tarpon, disrupted the alleged conspiracy before the shipment reached New Zealand.

Swinton lives in the Bay of Plenty and worked casually for C3 Ltd, a stevedoring business contracted to the Port of Tauranga. C3 declined to comment on the arrest.

Rochelle Lockley, a spokeswoman for the Port of Tauranga, said none of its 250 employees were implicated, although up to 6000 people regularly enter the port to work for other employers.

"Everyone who wants to access the port has to do a safety induction and be issued with photo identification linked to their employer," Lockley said.

"They must show the ID to get through the security gate and we can (and do) withdraw access for suspicious or unsafe activity on site."

Any vehicle on site could be searched at any time, and Lockley said the port was patrolled 24/7 by Customs, police officers, and the port's security team which is trained in detecting explosives, firearms and drugs.

"On top of that, the whole site is under surveillance by high-definition security cameras," Lockley said.

Police and Customs spokespeople declined to comment because the matter is now before the court.

Although New Zealand has a reputation as one of the least corrupt countries in the world, the arrest of the port worker is the latest in a series of incidents which show the threat of organised crime is significant.

Among the incidents the Herald has reported on in recent months were a police recruit filmed taking drugs with the Comancheros motorcycle gang, a police officer jailed for leaking intelligence to a gang, Air New Zealand baggage handlers arrested for allegedly helping someone to smuggle drugs into the country during a Covid-19 lockdown.

And in an extraordinary heist, a suspicious shipping container linked to the Mongols motorcycle gang also disappeared from the Ports of Auckland on the back of the truck in the middle of the night. A shoebox filled with $90,000 was found in the home of a senior staff member at the port.

Police and Customs have long warned of the risk of bribery and corruption among law enforcement and the business sector, and say the recent arrival of gangs such as the Comancheros and Mongols from Australia has heightened that threat.

"This kind of corruption is not unheard of internationally but New Zealand has been isolated from it for a long time," Bruce Berry, the head of investigations for Customs told the Herald in September when discussing the shipping container that vanished.

"Now, we've been thrust into this space very quickly with the arrival of the '501s', with their greater sophistication and international connections. It's a scary story."

The "501s" are deportees from Australia, nicknamed after the section of the immigration law used to remove them on character grounds.

Among the thousands forcibly evicted to New Zealand over the past five years are dozens of members of Australian gangs such as the Mongols, Comancheros, Bandidos and the Rebels.

Although a small fraction of the "501" deportees, Kiwi law enforcement agencies believe these new gangs have a disproportionate influence on the criminal underworld because of their international organised crime links and sophisticated techniques, including use of encrypted phones.

In response to the potential corrupting influence of the Australian newcomers, the police established a National Integrity Unit last year to investigate links between officers and gang members.

"The deportees are bringing a different mindset. They need people like police officers, officials in other government agencies, to enable them to conduct business, Detective Superintendent Iain Chapman said at the time.

"So we'll investigate those links, but we're educating our staff so they can be aware of the risks and protect themselves."

An organised crime figure approaching a police officer with an intent to corrupt them was never obvious, Chapman said.

"It's subtle, friendly, discreet. No one wakes up in the morning deciding to be corrupt ... it's a slow burn, and we have to make our staff aware of what that looks like."