Boris Johnson said the UK did not learn the lessons of past pandemics in developing sufficient capacity for testing and tracing.
The Prime Minister said it was a “brutal reality” when responding to MPs in the Commons Liaison Committee on Wednesday.
Answering a question from former health secretary Jeremy Hunt, he said: “We did have a test, track and trace operation but unfortunately we did not have the capacity in Public Health England.
“To be absolutely blunt, we didn’t have the enzymes, we didn’t have the test kits, we just didn’t have the volume, nor did we have enough experienced trackers ready to mount the kind of operation they did in some other East Asian countries, for instance.
“And I think the brutal reality is this country didn’t learn the lessons of Sars or Mers and we didn’t have a test operation ready to go on the scale that we needed.”
After the Government previously set a target of 100,000 tests a day, a second target of a 200,000 daily testing capacity was set for the end of May.
However, less than a week before Monday’s deadline, Health Secretary Matt Hancock said the NHS in England had the capacity to conduct 161,000 tests a day.
He told the Downing Street briefing on Wednesday: “Because of that increased capacity, I can announce that we’re expanding eligibility yet further.
“From tomorrow, we’re expanding eligibility for testing to include the under-5s so that every single person who has symptoms of coronavirus can get a test, no matter their age.”
A test-and-trace operation is now set to be implemented on Thursday after widespread contact tracing was previously abandoned in mid-March.
Mr Johnson also told the committee that the UK is testing more people than any other country in Europe.
But testing figures collated by University of Oxford-affiliated Our World in Data, suggest several other European countries have higher testing rates.
As of May 22, rolling seven-day average data shows Lithuania had tested 2.25 samples per 1,000 people, Italy had performed 1.05 tests per 1,000 people, and the UK had tested 1.01 people per 1,000 people.
The calculation is based on the number of tests reported by most countries but uses the UK’s figure for the number of people tested and is given as a seven-day rolling average.
Mr Johnson’s statement came shortly after the Department of Health announced it was temporarily pausing announcing figures on the number of people who have been tested for coronavirus due to a “small percentage” of duplicates.
Since early in the outbreak, the Department of Health has published a daily update on Twitter with figures including the number of hospital deaths and total cases.
However, since May 23, figures on the number of people tested have not been published, with technical difficulties referenced on each of the daily tweets.
On the tweet posted on May 27, a footnote read: “Reporting on the number of people tested has been temporarily paused to ensure consistent reporting across all pillars.
“This is due to a small percentage of cases where the same person has had more than one test or tested positive more than once for Covid-19.”
As of 9am 27 May, there have been 3,798,490 tests, with 117,013 tests on 26 May.— Department of Health and Social Care (@DHSCgovuk) May 27, 2020
267,240 people have tested positive.
As of 5pm on 26 May, of those tested positive for coronavirus, across all settings, 37,460 have sadly died. pic.twitter.com/BeUZvwTnqq
On Tuesday, the Department of Health declined to say what technical difficulties had affected previous counts.
A daily tally of coronavirus tests is still being provided, but not the breakdown of how many people this includes.