The Government is trying to determine how much infant formula is affected after China apparently changed its mind on allowing in product from unregistered companies.
China introduced a register of infant formula manufacturers on 1 May. Five of New Zealand's 13 manufacturers and ingredients manufacturers gained approval and were registered, and 35 formula brands aligned with approved manufacturers can continue exporting.
The Ministry for Primary Industries had believed China would allow in formula made before May, even from unregistered companies. The ministry now says that was not the case.
It does not yet know how much product is affected and is working with officials in China to get exemptions granted for product already on the way there.
Primary Industries Minister Nathan Guy said the Government was still trying to determine the extent of the problem.
"It would be we think, not a huge amount of product, because we're talking just in the last couple of weeks and bearing in mind that we've got 90 percent of those manufacturers already approved on the first of May."
The chairperson of the New Zealand Infant Formula Exporters Association, Michael Barnett, said the move by Chinese certification body CNCA blindsided the association's members.
"We have no say. We'd love to be in the room so we could talk to CNCA and to be able to have them understand the quality of what we can do, the safety that we can offer ... but we're in the hands of