Allowing only essential freight to be transported to businesses by road, not that simple, haulage organisation warns.

A "pile-up" is looming at the country's ports that will restrict the movement of food and medical supplies if non-essential freight destined for closed businesses can't be cleared, Road Transport Forum chief executive Nick Leggett has warned.

"All manner" of freight could arrive at the same time on cargo ships, he said.

"We now have a situation where many businesses that receive some of that freight are closed and there is nowhere for it to go," he said.

"The issue with non-essential goods is you can remove them from the port, but if there's nobody at the receiving end at work, where do you put them?'

The Government needed to recognise that "all freight must move" during New Zealand's coronavirus lockdown, and not just essential items, Leggett said.

READ MORE:

* Live: Coronavirus updates

* Consumers will be able to shop online only for essentials during lockdown

​* Coronavirus - Truckers call on Govt to provide more clarity on what's an essential delivery

He forecast "constipation" at the ports and massive problems, if the issue wasn't addressed.

"This an absolute real live thing."

SUPPLIED Containers need to be cleared and emptied to ensure essential supplies can get in and exports can get out, Road Transport Forum chief executive Nick Leggett says.

​Mainfreight chief executive Don Braid said it wasn't seeing congestion yet, but the forum was "making good points".

"Under the lockdown rules, it is not possible to deliver non-essential freight."

A successful outcome would require "innovative thinking and action", he said.

"We are attempting to assist the government agencies through this where we can."

Leggett said officials at the Transport Ministry had "definitely listened" to the forum's concerns, but had said the rules stood at this point.

"If it is deemed by the Government to not be essential, it cannot be moved.

"We absolutely appreciate the reasons for that but if we don't have an 'all-of supply' chain solution to this we believe there will be issues in a couple of weeks," he said.

Some ports would be struggling "even by the end of the week", he said.

Transport Ministry supply chain manager Harriet Shelton responded to the forum's concerns with an update that said its lockdown rules did allow the movement of non-essential goods "if necessary to move or create space for essential goods".

Leggett said the forum would not have put out its warning lightly at this time.

Reopening closed businesses to accept non-essential freight would "fly in the face" of the reasons for the lockdown, which were to keep as many people home as possible, he said.

"We do appreciate that, but we need a solution."

Leggett said another problem was that if containers in which non-essential goods were imported were not emptied, there would be a shortage of containers for exported goods going out.

"All freight needs to move during this time to enable the valuable exports that are going out, such as kiwi fruit, access to ports."

MATT SHAND/STUFF Port of Tauranga says non-essential freight can be stacked next to its terminals but will then take time to retrieve, so it is important essential goods are identified first.

Customs Brokers and Freight Forwarders Association chief executive Rosemary Dawson agreed that the delivery of non-essential cargo remained an issue that would need to be dealt with to avoid congestion.

"Sea freight was operating fairly normally now," she said.

But Dawson said she "absolutely" shared some of the concerns expressed by the Road Transport Forum, including with regard to the availability of empty shipping containers.

Port of Tauranga chief executive Mark Cairns said it had put in place new measures to allow importers to identify imported cargo required for essential services before it arrived in New Zealand "so that it can be handled and transported first".

It needed the support and co-operation of importers and exporters to help it manage the flow of cargo "and avoid blocking the path of essential food, medicine, equipment and other supplies", he said.

CHRIS HUTCHING/STUFF Mainfreight chief executive Don Braid says the Road Transformation Forum is making good points and innovative thinking will be needed.

Non-essential imported cargo could be temporarily stored on or off-site until it could be collected by truck or transferred by rail to MetroPort Auckland, he said.

Spokeswoman Rochelle Lockely said non-essential freight could be stored near its terminals in Auckland and Tauranga, but once freight went into that "locked stack" it would not be fast to retrieve, so it was important essential items were identified first.

There was a worldwide shortage of shipping containers because of the disruptions caused to supply chains globally by the coronavirus, but that was not something the port had detailed information on, she said.

The port would not charge extra fees for storing non-essential cargo until April 26, apart from one-off handling charges and for power charges needed to keep refrigerated containers cool, Cairns said.

The Road Transport Forum has suggested that some goods that can't be delivered to closed businesses could be stored on land owned by Kiwirail, but Leggett believed that could only be part of any remedy.

"Closing down the country to the scale we have now hasn't been done before and it does reveal some issues that need to be addressed pragmatically," he said.

To illustrate the problem, Leggett said 14,000 cars were expected to arrive from Asia over the next month.

"Those cars cannot stay on the port; they have to go somewhere. The dealers that would normally take them are closed.

"We appreciate cars are not an essential service, however, they are holding space that is needed for essential goods.

"Our industry is looking at how we could find storage for the freight with nowhere to go, but we need the Government to allow that freight to move," he said.

Leggett said some truck drivers had been stopped by police and asked what they were doing on the roads.

"Well, they are doing a job and it is one that is essential at a time like this.

"They cannot be forced by the Government to be arbiters of what is essential and non-essential on the back of their truck," he said.