DHBs have been asked to put some face masks on hold while the Ministry of Health investigates concerns around their quality.
The concerns about the 4.9 million masks relate to inconsistencies in labelling and certification, the ministry said.
They were bought internationally to ensure New Zealand had a steady supply of personal protective equipment (PPE) during the Covid-19 pandemic.
"New Zealand continues to have sufficient supply of PPE, including masks, which is distributed at a national level," the ministry said.
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Pressure on global supply lines in March meant PPE was being purchased quickly and often from different sources than those usually used in the health sector.
The ministry has reviewed all orders as part of routine due diligence to ensure quality and authenticity of PPE.
"DHBs that have received the masks of potential concern have been asked to put those items on hold while further quality checks are completed [as] a precautionary move. It does not mean that these items are non-compliant."
The masks will be restocked. The ministry's national store and DHBs have 50 million masks and 90 million are on order.
Earlier in the pandemic tens of thousands of older masks were found to have crumbling elastic.
South Canterbury DHB's entire pandemic stock of 58,000 N95 masks was replaced because of their age. Some had been bought as far back as 2005.
*An earlier version of this article included a video with products which were not related to the Ministry of Health's review.