The Department of Health and Social Care (DHSC) insists that the capacity of the NHS Test and Trace system is at the highest it has ever been , but said there has been a “significant” demand for tests.
This includes demand from people “who do not have symptoms and are not otherwise eligible”, the DHSC said.
Leaked documents revealed the 185,000 backlog, as well as the fact that tests are being sent to laboratories in Italy and Germany, according to The Sunday Times.
The DHSC said it plans to rapidly expand capacity in the coming weeks and new technology will be brought in to process tests faster.
Regarding tests being sent abroad for processing, the DHSC said the public expects them to be doing everything they can to respond to the pandemic, including working with a wide range public and private sector partners.
The Sunday Times also reported that documents show there has been an increase in tests being voided.
The newspaper said Randox disposed of 12,401 used swabs in a single day on September 2, and has voided more than 35,000 used test kits since the start of August.
In a statement, Randox said a small minority of samples may be voided for reasons such as leaking or damaged tubes, or have time expired.
“Those being tested are made aware that samples only remain valid for a limited period once collected, and those periods of validity are fully understood across the planning and logistic process.
“Randox have no responsibility for the logistics of sample delivery to laboratories,” the statement said.
Many people who tried to access tests this week were met with an error message telling them to try again, and warning them not to call the helplines.
And on Tuesday, NHS Test and Trace’s director of testing apologised to people who were unable to get a test.
Transport Secretary Grant Shapps said on Thursday that 1.2 million tests are being carried out per week at the moment, adding that there is a capacity for 300,000 per day.
The Government no longer publishes daily testing figures, but the latest available figures say 175,687 tests were reported on September 2.
And, on the same date, the estimated total capacity reported by laboratories was 369,937.
In May, it emerged that around 50,000 coronavirus test samples had to be sent from the UK to the US after “operational issues” in the lab network led to delays in the system.
At the time, the Department of Health said sending swabs abroad is one of the contingencies to deal with so-called teething problems in a rapidly-expanded testing system.
In a statement on Sunday, DHSC said: ““NHS Test and Trace is working and our capacity is the highest it has ever been but we are seeing a significant demand for tests including from people who do not have symptoms and are not otherwise eligible.
“New booking slots and home testing kits are made available daily for those who need them and we are targeting testing capacity at the areas that need it most, including those where there is an outbreak, and prioritising at-risk groups.
“Our laboratories are processing more than a million tests a week and we recently announced new facilities and technology to process results even faster.
“If you do not have symptoms and are not eligible to get a test you can continue to protect yourself if you wash your hands, wear a face covering and follow social distancing rules.”