A Newshub investigation into the Customs Service has revealed new concerns at the country's sea ports.
This time, our sources tell us it's the containers which are not being searched well enough.
Whistleblowers have told Newshub that even though at least 645 containers arrive at the Ports of Auckland every day from all over the world, on average only one is being opened up and searched every month.
"Only about one in four containers coming into the country actually gets screened properly," says NZ First MP Richard Prosser. "So the fact it's been cut down below that is a major source of concern."
Containers at the Port also get X-rayed using this truck. It's a machine like this one which helps Customs officers inspect cargo for suspicious material.
But even that type of screening is limited -- Newshub been told only around five to seven are X-rayed every day, out of more than 600.
Our whistleblower says staff would like to search more but they're not being asked to, and there's fewer staff.
"The container facility down at the Port can only hold three or four containers," the whistleblower says. "They can only unpack around one or two a day."
It's a similar story at Lyttelton Port, the South Island's major gateway for international trade.
We've been told: "Customs used to X-ray 30 a week [at Lyttelton], now it's only around three". A union representing a third of all officers says the lack of resources is a serious issue.
"The feedback we're getting is consistent with what the whistleblower is saying, that our members are concerned about pay and they're concerned about staffing," says Glenn Barclay, National Secretary of PSA.
Mr Prosser says it's down to the Government to fix it.
"It's the Government that needs to answer and the Government which needs to put more resourcing into this problem," he says.
Newshub asked Customs for a response, but by the end of the day they hadn't gotten back to us. We also asked to interview the Customs Minister Nicky Wagner -- she said she was too busy, but she still has confidence in the organisation.
Newshub investigations this week have revealed staffing and enforcement issues not only at sea ports but also the airport.
Clearly frustrated, one of the six officers who have contacted us said: "If I was a drug courier, I would take a punt at bringing drugs through the airport."