Tens of thousands of rapid antigen tests have been seized at the borders in what a school principal calls "nonsensical" bureaucracy.
At least 30,000 rapid tests were seized in the first eight weeks of the year.
New Zealand has only approved 11 rapid antigen tests for use, but Australia has approved 32.
And the Covid-19 test varieties not approved in New Zealand can be seized, even if they're regarded as reliable and safe in Australia or other countries.
Answering a written Parliamentary question from Act leader David Seymour, Minister of Customs Meka Whaitiri said 31,156 rapid tests were intercepted and seized in the year to February 22.
Auckland Grammar School headmaster Tim O'Connor said the situation was absurd.
Grammar ordered JusChek rapid tests which Australia's Therapeutic Goods Administration approved for use in mid-February.
O'Connor said the school wanted to be proactive about offering students and staff another layer of protection, but bureaucracy stymied those efforts.
The JusChek kits arrived at Auckland Airport but then the school was told Customs would not allow the kits through.
"We've tried explaining that they're just for school use," O'Connor added.
He said the rapid tests were sent back to Australia, where they were now being used.
"It's just nonsensical, right? It beggars belief when we're all trying to do the best we can."
Act leader David Seymour said the bans and confiscations of so many test types symbolised the Government's Covid-19 response.
"It's far too centralised, it's far too controlling. There's not enough partnership with business and society."
He said in relation to rapid tests, Australian health regulators had high standards, but were able to approve more tests.
Australia's Therapeutic Goods Administration has approved multiple rapid tests not available in New Zealand, including some deemed "very high sensitivity" or most reliable.
"Why wouldn't you open supply for more types of tests?" Seymour added.
One pharmacist described "desperation" from the public for rapid tests this week.
Members of the public can buy RATs from pharmacies, supermarkets and big box outlets.
Whaitiri said pandemic response laws meant only authorised rapid tests could be imported, distributed, supplied or used, even for personal use.
In her written response, she said Customs could check if goods complied with relevant import or export requirements.
"These interceptions may be released, provided the necessary authorisations and approvals are met, or they may be seized if the required authorisation is not granted due to the requirements not being met."
The minister added: "All goods that are seized are held for a period of time, pending any requested reviews of the seizure."
If no application was made to review seizures, ownership of the goods was transferred to the Crown, and Customs could destroy or dispose of the tests.
Yesterday, the Ministry of Health revealed there were 18,833 community cases of Covid-19 in the community - a decrease in daily cases from recent days above 20,000.
But health chiefs have sounded the warning bell over fears people are not reporting positive results from rapid antigen tests - and say that could be the reason for the apparent dip in numbers.
"While decreases in cases can be encouraging, the Ministry of Health urges caution," it said.
"We are expecting cases to jump around, and are continuing to see increases in Covid-19 related hospitalisations.
"Additionally, public health officials consider that one possible reason for the decrease in cases could be related to people not self-reporting rapid antigen test results.
"The Ministry of Health would like to remind everyone to self-report both positive and negative results for RATs through My Covid Record, to help health officials understand the size and trends of the outbreak."
People who are symptomatic or a household contact, can order RATs through the newly launched RAT requester site.