Tens of millions of British-made lateral flow tests were trapped for months in storage while bosses waited for government approval.
Derby-based SureScreen Diagnostics produced the first UK-manufactured, UK-approved LFTs, and signed a £503m contract with the government last February.
But a source claimed millions of LFTs were held at a warehouse for three months in the run-up to Christmas - just as people in England faced a nightmare getting hold of tests.
The source told the Mirror the firm had waited months for the government to sign off the packaging design, and the delay was “baffling” and “frustrating”.
The tests - which were held at a business park in Nottingham - are now being distributed.
The UK Health Security Agency did not dispute claims that around 30million SureScreen tests were held in storage, or that the delay was around three months, or that a wait for the packaging to be approved was one reason.
However, officials stressed the LFTs themselves also had to undergo rigorous checks by Porton Down and the Medicines and Healthcare products Regulatory Agency (MHRA).
SureScreen director David Campbell tonight revealed it had taken six months to get approval for the tests themselves, which finally came in November.
Since then the firm has been dispatching lorries full of tests to national distribution centres, but was still waiting for the official announcement that they were approved for use.
The company released photos to Sky News showing millions of tests being stored in towering shelves almost to the roof of the Nottingham warehouse.
A UKHSA spokesperson said: “LFDs have not been held in storage solely because government approval of packaging designs were outstanding.
“Extensive evaluation is carried out on tests designed for home use to ensure they are reliable and accurate.
“Evaluation of this data is part of the regulatory approval process can take several weeks.”
It came as Labour today accused authorities of “delaying approval” for British-made tests.
Shadow business minister Bill Esterson waved a box of lateral flow devices in the Commons, saying: "Buying British is a great way for the Government to boost productivity.
"So why are they buying so many Covid tests from China, many of which only have temporary MHRA approval and are now banned in the United States?
"In contrast, the MHRA is delaying approval for British test manufacturers who have approval and are able to sell around the world but not here."
Tory MP Richard Fuller added the approval process had had a "chilling effect" on UK manufacturers and demanded a review.
Business Secretary Kwasi Kwarteng said the UK has "led the world" in life sciences and manufacturing, but failed to answer the questions put to him by Labour.
David Campbell, Director of SureScreen, admitted the approval of the tests themselves had taken “longer than we expected” and “as a result, we had some stock of devices ready to go upon being granted approval”.
He said: “All tests for home use in the UK have to go through stringent clinical trials and usability evaluation to ensure that they are fit for purpose and ensure there is no risk to the end users of the devices.
"All of this data is then submitted to regulatory bodies for evaluation and approval before the test can be placed on the market and used.
"As you might expect, completing these studies can take time.
"In our case this process took longer than we expected and, as a result, we had some stock of devices ready to go upon being granted approval.
"This meant we were able to move very quickly as soon as we received the approval and the kits are now being distributed throughout the UK.”
