Surge testing will begin in parts of east London after several cases of the South African and Brazilian variants of coronavirus were detected, according to the Department of Health.
NHS test and trace will be working with the council in Tower Hamlets to provide extra testing in the E1 postcode from Sunday, along with genome sequencing, which helps establish the variant that someone has been infected with.
Authorities did not say how many cases of the variants had been discovered, saying only that several cases of the B.1.351 strain first recorded in South Africa and the P1 stain first recorded in Brazil had been identified.
All confirmed cases are now self-isolating, the department said. It also said there was no connection between the cases discovered in east London and the cluster found in south London recently.
Everyone who lives, works or studies in the E1 postcode, and is over the age of 11, is being encouraged to get tested, even if they are not displaying symptoms.
The news came as the government announced that a further seven people had died within 28 days of testing positive from the virus, taking the total UK death toll to 127,524.
As of 9am on Saturday morning, a further 1,907 cases of the virus had been lab-confirmed in the UK, taking the total number of infections to 4,418,530.
The latest government data, recording up to Friday, showed that 49,287,257 coronavirus vaccines have now been administered in the UK.
Since the previous day, a further 129,657 first dose jabs have been recorded, taking the number of first doses administered in the UK to 34,346,273, and another 405,456 second doses, taking the total to 14,940,984.
As a percentage of the UK population, this means that 51.4% of people have now received a first dose, and 22.4% are fully vaccinated.