A cargo ship carrying 23,000 tonnes of palm kernel has anchored off the New Zealand coast after being barred from the Tauranga Port.

Frustrated animal feed merchants say the blocked importer of 23,000 tonnes of palm kernel extract should have immediately ordered the ship to turn around and leave New Zealand waters when its biosecurity paperwork was found to be defective.

Instead the vessel carrying the controversial feed (PKE) has been sitting off the Bay of Plenty coast for nearly a month, while the Ministry for Primary Industries (MPI), tries to negotiate a resolution with the importer, which it has refused to name.

The importer is understood to be the New Zealand division of American feed supply giant ADM.

DOMINICO ZAPATA/FAIRFAX NZ MV Molat, a cargo ship carrying a load of palm kernel extract at anchor 4km off the Mount Maunganui coast.

Labour spokesman for primary industries and biosecurity Damien O'Connor said he understood from reliable information that the importer was ADM.

READ MORE: Decision soon on ship carrying palm kernel extract

MPI stopped the ship, MV Molat, unloading at the Port of Tauranga early last month as a biosecurity risk because most of the PKE aboard could not be shown to be from Malaysian PKE processing factories approved and registered by the Malaysian government, a requirement of MPI clearance.

It is understood some of the PKE was from an approved source and was allowed to be taken off. MPI said on Monday a decision on the cargo's future was imminent, but on Tuesday it said it had no update on the issue.

PKE is a by-product of the palm oil industry which has been linked to the destruction of rain forests and blamed for destroying the Borneo and Sumatra habitats of endangered orangutans.

Greenpeace tracked the MV Molat from Malaysia to New Zealand.

Unregistered PKE sources are considered a biosecurity risk as the feed can carry diseases which could severely damage New Zealand's agricultural economy.

New Zealand PKE importers who declined to be named said they were unhappy the importer's anonymity meant they had all been associated in the public mind with the debacle when they would only ever use registered Malaysian processors.

One industry source said the importer should have shown more respect for New Zealand's biosecurity laws by immediately returning the cargo to Malaysia.

"I'm sure there's nothing wrong with the shipment, it'll be just a paperwork oversight but it was just arrogance on behalf of a huge American corporate not to get the ship out of there straight away," he said.

The cost of doing that would have been "pocket change" to the importer, he said.

"It's like turning up in New Zealand without a passport and expecting to get in. The paperwork problem should have been picked up long before the boat got here."

The publicity created by the situation would just stir up concerns about PKE again, a feed that had helped thousands of dairy farmers get through the worst of the industry downturn.

The importer of the blocked cargo had only a small share of the New Zealand market, he said.

ADM is a New York stock exchange-listed company with revenue last year of US$67.7 billion (NZ$93b). Its New Zealand office is at Mount Maunganui. It did not respond to requests for comment.

A spokesperson at ADM's Chicago headquarters said the company did not comment on commercial matters.

New Zealand feed industry sources said PKE supply here was currently tight. One source said he was mystified if the importer had used an unregistered Malaysian PKE processor or processors when there were plenty of approved plants to source from. It was more than likely the blocked feed had come from several sources and was mixed up in the ship's hatches.

MPI was applauded for its action in blocking the ship. Industry sources said the time being taken to clear up the matter was because MPI would require an audit of the Malaysian source factory or factories and then letters from appropriate authorities would need to be exchanged to meet New Zealand's biosecurity requirements.