The government's coronavirus testing programme is in chaos – with leaked documents revealing a backlog of 185,000 swabs and large numbers of people who will never receive their results.
Officials apologised this week over growing problems with the test-and-trace process, blaming a "critical pinch-point".
And with infections soaring across the UK, leaked documents show the system is currently so stretched that it is sending samples to laboratories in Italy and Germany.
Labelled "official: sensitive", the Department of Health and Social Care report seen by The Sunday Times says most British laboratories are processing fewer tests than their stated capacity due to problems in supply chains.
The newspaper said that despite government claims that its system has capacity for 375,000 tests a day, the equivalent of just 62,000 people a day were newly tested in the first week of September.
It reported people across the country struggling to get tests, with some being told to drive hundreds of miles to do so.
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Suspected coronavirus patients in London have received "no test sites" found messages when repeatedly trying to arrange checks to confirm they have the disease.
And tests have even been unavailable to many people in areas covered by stricter lockdown measures due to high numbers of infections.
According to leaked figures, three-quarters of all tests miss government targets of 24 hours from booking to result – while one in four take longer than 48 hours.
The Sunday Times report said the number of tests being "voided" – disposed of due to human or technical error – had risen sharply.
Randox, which the government gave a £133m testing contract to early in the pandemic, reportedly disposed of 12,401 used swabs in a single day on 2 September and has voided more than 35,000 used test kits since the start of August.
The company said in a statement that "a small minority of samples may be voided for reasons such as leaking or damaged tubes, or have time expired".
Jon Ashworth, shadow health secretary, told the newspaper: "People ill or with a sick child desperate for a test will be astonished that tests are piling up, left unprocessed, or even thrown away, because of errors in transportation and swabbing, while at the same time we are testing less than capacity.
"This really is ministerial incompetence at a whole new level."
Mr Johnson denied the testing programme was mired in crisis this week, after Labour leader Sir Kier Starmer told him: "This is basic stuff, people who have got COVID symptoms are very anxious about themselves, their children, their families and what to do, it means they can't go to work, they can't send their children to school, it matters."