Around £1.4billion of personal protective equipment (PPE) from a single firm has been destroyed or written off, it has emerged.
While the stock was manufactured to the proper standard, it has been disposed of after it was deemed surplus to requirements.
Critics yesterday branded the move a 'staggering waste' and a 'colossal misuse of public funds'.
Figures from NHS Supply Chain show Northamptonshire-based company Full Support Healthcare supplied at least 1.57 billion items of personal protective equipment that will never be used.
The company struck a £1.78 billion deal with ministers to supply face masks, aprons, eye protection and respirators in April 2020.
It is understood to be the largest Covid-19 PPE order, accounting for 13 per cent of the Government's total spend.
Around 1.57billion pieces of personal protective equipment worth £1.4billion supplied by Full Support Healthcare has been destroyed or written off
There is no suggestion the company has acted improperly.
Responding to the revelation, Labour's health secretary Wes Streeting said: 'We know that billions of pounds were wasted during the pandemic on corruption and incompetence by the Conservatives, but this is the worst example I have ever seen.
'£1.4billion on one contract, paying for PPE that was never used, and Rishi Sunak's fingerprints are all over it.
'That is money that could have been used to pay the salaries of 37,000 NHS nurses.
'It is staggering waste, and we need a full and frank account as to how so much public money was thrown down the toilet.'
Daisy Cooper, deputy leader of the Liberal Democrats, said: 'This is just the latest in a series of damning revelations on the Conservatives' record of mishandling Covid contracts.
'Instead of this troubling pattern of waste, shortcuts and lack of oversight, the public deserve transparency on the true cost of these failures.
'The Liberal Democrats would take steps to ensure such a colossal misuse of public funds never happens again.'
NHS Supply Chain, which manages the distribution of medical supplies to hospitals and other care providers, supplied the figures in response to Freedom of Information Act requests from the BBC.
The responses showed that of the 2.02 billion items of PPE provided by Full Support Healthcare, only 232 million items have been dispatched to the NHS or other care settings.
It is understood about 749 million items have already been burned or destroyed, while a further 825 million are classified as excess stock.
This is just the latest in a series of damning revelations on the Conservatives' record of mishandling Covid contracts.
According to the report, the Government had previously estimated about £85 million worth of PPE secured under the contract would not be used.
The BBC reported that at least £100 million of additional public money has been spent on storing and incinerating the excess stock since its purchase.
A Department of Health and Social Care (DHSC) spokesperson said: 'We do not recognise the £1.4 billion quoted.
'Our position on PPE stock is set out in the department's annual accounts as audited by the National Audit Office.
'PPE was secured at the height of the pandemic, competing in an overheated global market where demand massively outstripped supply.
Labour shadow health secretary Wes Streeting called the contract a 'staggering waste' and said a 'full and frank' account into the mishap was needed
'Nearly half of all the remaining stock was sold, recycled, or donated by the department.
'In line with our reduction of storage and disposal strategy unused items will be turned into energy from waste which will see the department recoup further costs.'
In January, DHSC accounts revealed some £9.9 billion of the £13.6 billion spent on PPE had been written off as some items were defective or not suitable, while others will not be used before their expiry date.
An accountability report by the National Audit Office said that the department plans to dispose of 'nearly all' of its current PPE stock held in warehouses and containers.
At the time, Downing Street defended the losses by stressing the circumstances the Covid-19 pandemic caused, such as PPE being in short supply leading to a hike in costs.