Fifty million face masks bought by the government in April will not be used in the NHS because of safety concerns.
The government says the masks, which use ear-loop fastenings rather than head loops, may not fit tightly enough.
They were bought for healthcare workers from supplier Ayanda Capital as part of a £252m contract.
Ayanda says the masks met the specifications the government had set out. The government says its safety standards process is “robust”.
It has emerged that the person who originally approached the government about the deal was a government trade adviser who also advises the board of Ayanda.
But he told the BBC his position played no part in the awarding of the contract.
Calling for a National Audit Office investigation into the government’s “mishandling of PPE procurement”, Labour MP Rachel Reeves said: “The latest PPE scandal cannot be swept under the carpet.”
In the early weeks of the pandemic the NHS experienced severe shortages of personal protective equipment (PPE).
The government says it had to find new suppliers quickly to meet demand and to compete with rising global competition.
On 29 April the Department of Health and Social Care signed the £252m contract with Ayanda Capital Limited to supply two types of face masks.
The most expensive part of the order consisted of 50 million FFP2 respirator masks, which are designed to protect healthcare workers from inhaling harmful particles.
According to legal papers seen by the BBC, the government says these masks will now not be used in the NHS because of a safety issue.
The document says that there is concern about whether they would fit adequately.
To be effective these types of face mask need to fit tightly to create a seal between the mask and the wearer’s face.
Anyone who wears them for work is required to undergo a face fit test.
“The face fit is either a pass or a fail and there are more fails on products with ear loops than there are on products with head harnesses,” says Alan Murray, chief executive of the British Safety Industry Federation.
“That means that it wouldn’t necessarily provide the protection that was required from it.”
It is not clear what will happen now to the 50 million masks.
Ayanda Capital also supplied 150 million Type IIR masks, which the government says are unaffected.
Most have now been delivered but they have not yet been released for use in the NHS and are awaiting further testing.