The Ministry of Health has identified concerns with the quality of 4.9 million masks purchased internationally as part of New Zealand's response to Covid-19.
In a statement, the Ministry said the concerns related to inconsistencies about labelling and certification.
It said because of global pressure on supply lines, personal protective equipment (PPE) such as masks were purchased quickly and often from different sources than those usually used in the health sector.
"The Ministry has reviewed all PPE orders since the start of the year as part of routine due diligence to ensure quality and authenticity of PPE," the statement read.
"DHBs that have received the masks of potential concern have been asked to put those items on hold while further quality checks are completed."
The ministry said putting the circulation of masks on hold was a precautionary measure while they undergo further quality assurances.
It said it does not mean the masks are non-compliant.
The ministry said New Zealand continued to have a sufficient supply of PPE, with national stores and DHB reserves holding 50 million masks, and another 90 million masks were on order.