Liverpool on Friday began England's first city-wide trial of coronavirus testing in an attempt to prevent hospitals becoming overwhelmed during the country's second wave of the pandemic.

All of the northwestern city's 500,000 residents as well as people working there will be offered repeat tests, even if asymptomatic, under the pilot, which will initially run for two weeks.

Liverpool last month became the first region to enter the most severe tier of regional lockdown as it battled a spike in cases, followed by the nearby city of Manchester.

A month-long nationwide lockdown came into force on Thursday as cases began to spiral in all parts of England.

Britain is already grappling with the worst toll in Europe with over 48,000 dead after testing positive for the disease.

Liverpool mayor Joe Anderson said the pilot could save lives and "get the city out of tier three restrictions".

Matthew Ashton, the city's director of public health, told the BBC the pilot could last longer, saying they "want to make sure it is long enough for us to be able to see the impact".

"The point of this is to get the city tested," he said.

Prime Minister Boris Johnson said the kind of cheap new tests being deployed in Liverpool "can be a massive and possibly decisive use to us in this country in defeating the virus".

The tests involve swabs and new "lateral flow" tests, akin to pregnancy tests, which can provide a result within 20 minutes. 

New testing sites have been set up across the city, in schools, universities, offices and care homes, with the help of around 2,000 military personnel.