"Sadly, the tests we have looked at to date have not performed well," he wrote in a blog post entitled 'Trouble in testing land'. "We see many false negatives (tests where no antibody is detected despite the fact we know it is there) and we also see false positives.

"None of the tests we have validated would meet the criteria for a good test as agreed with the Medicines and Healthcare Products Regulatory Agency (MHRA). This is not a good result for test suppliers or for us."

Last month, the Government ordered 3.5 million fingerprick tests, mainly from Chinese manufacturers, and later placed provisional orders for 17.5 million tests from nine firms including some based in the UK. None of the tests were found by Oxford to be reliable enough for mass use.

Sources said the Government would now work with the manufacturers to improve reliability, but Prof Bell suggested it could be time to go back to the drawing board and work to develop a test from scratch.

"There is a point in evaluating these first-generation tests where we need to stop and consider our options," he said, adding that the search was on for a test sensitive and specific enough to mean it could be taken at home.

"That should be achievable, and the Government will be working with suppliers both new and old to try and deliver this result so we can scale up antibody testing for the British public," he said. "This will take at least a month."

Ministers reportedly spent millions of pounds of taxpayers' money on the initial order of 3.5 million tests from two Chinese manufacturers, Wondfo and AllTest, which already have EU approval for use.

Last month, the Spanish government withdrew 58,000 Chinese-made coronavirus testing kits from use after it emerged that they had an accurate detection rate of just 30 per cent.