Everyone in Liverpool will be tested for Covid-19 as armed forces arrive to launch the first whole city testing operation.
Some half a million people are to be offered regular coronavirus testing in a pilot scheme.
It has been hailed as having the potential to be a “powerful new weapon” in the fight against the disease.
All residents and workers in Liverpool will be offered repeat testing whether or not they have symptoms, the Department of Health said.
If successful in Liverpool, the programme will be rolled out across the rest of the city region and then in other areas of the country.
Prime Minister Boris Johnson said: “I want to thank the civic leaders of Liverpool for volunteering to join the UK’s first city-wide population testing pilot and the people of Liverpool for taking part.
“These tests will help identify the many thousands of people in the city who don’t have symptoms but can still infect others without knowing.
“Dependent on their success in Liverpool, we will aim to distribute millions of these new rapid tests between now and Christmas and empower local communities to use them to drive down transmission in their areas.
“It is early days, but this kind of mass testing has the potential to be a powerful new weapon in our fight against COVID-19.”
Mayor of Liverpool Joe Anderson said local leaders had made it clear to the Government they were “keen that we should be considered for any new strategies to tackle the worrying rise in Covid-19”.
The aim is to use new rapid turnaround tests – alongside existing swab tests, and Lamp (loop-mediated isothermal amplification) technology for NHS staff – to find asymptomatic cases in order to help prevent and reduce transmission in the community.
Health Secretary Matt Hancock said: “Last month we set out our ambition to use the latest mass testing technologies to bring this virus under control.
“Mass testing will help us to control this virus, by finding it even before people get symptoms.
“I’m delighted we can now roll out mass testing to whole cities – starting with the City of Liverpool.
“Using half a million of the very latest rapid tests, this rollout can help suppress the virus and give residents and workers some peace of mind.
“I want to thank local leaders, Mayor of Liverpool Joe Anderson and City Region Metro Mayor Steve Rotheram, and Liverpool’s Director of Public Health Matt Ashton, who will continue to work hand in hand with our dedicated Armed Forces to provide tests to anyone who wants one, fully supported by NHS Test and Trace.
“Everyone in Liverpool can help play their part by getting a test and following the rules, including the critical basics of hands, space, face.”
The new restrictions, announced by the PM in a televised press conference at the weekend, will be put to a vote in Parliament on Wednesday, but a growing number of senior MPs on the Conservative backbenches have indicated they will vote against them.
Any Tory rebellion is likely to be only symbolic, with Labour poised to back the Government on the measures.
Appearing in the Commons on Monday, Mr Johnson guaranteed “without a shred of doubt” the restrictions would expire on December 2, amid concerns from some Tories that England’s lockdown could be extended beyond that date.
He insisted technological advances will “defeat this virus by the spring” as he tried to ward off a rebellion over the stay-at-home order, which has seen the PM also come under pressure from business chiefs about the “truly devastating” measure.
He promised MPs a fresh vote on the next stage of measures to combat coronavirus, saying the intention is to return to a regional tiered system after this lockdown, and announced greater support for the self-employed after extending the furlough scheme for employees as pubs, restaurants and non-essential shops are ordered to close.
Meanwhile the Guardian reported the self-isolation period for people who test positive and their contacts could this week be cut to seven days.
Under current Government rules people who test positive for the virus must isolate for 10 days while their contacts must isolate for 14 days.
Speaking in the Commons, Mr Johnson said there would be a “big, big push” on the need for contacts to self-isolate, telling MPs “the proportion of people who are self-isolating in response to the urgings of NHS test, trace and isolate is not yet high enough”.
The PM, who will meet with his Cabinet on Tuesday morning, warned that “without action” there could be twice as many deaths over the winter as in the first wave, meaning there is “no alternative” but another national lockdown.
In a sobering message, he said Covid-19 presents an “existential threat” to the NHS, with doctors being forced to choose which patients to treat and “who would live and who would die”.