Surge testing is being expanded across parts of Lancashire after a number of cases of the Indian variant were detected.
People living, studying and working in areas including Burnley, Pendle, Hyndburn and Rossendale are being urged to take a PCR test even if they do not have symptoms.
The Department of Health and Social Care (DHSC) on Friday said that NHS Test and Trace was working in partnership with local authorities to launch additional testing and genomic sequencing across these areas.
Additional mobile testing units and Covid-19 tests are being deployed to higher educational settings in these areas while door-to-door testing is also taking place to find and isolate cases, it added.
The DHSC said the people who tested positive for the Indian variant have been told to self-isolate and their contacts are being identified.
Councils will confirm the areas where additional testing will be offered in their boroughs “shortly” and will also contact residents directly to ensure people come forward for testing, it added.
Along with increased testing in the Lancashire boroughs, so-called “enhanced contact tracing”, where tracers look back over an extended period of time to determine the route of transmission, will be used for those who test positive for a variant of concern.
People who have symptoms can book free tests online or by phone, while those without symptoms are advised to visit their local council’s website for more information.
The DHSC said: “The Government and its scientific experts are closely monitoring the evolving situation and rates of variants, and we will not hesitate to take additional action as necessary.”
The latest surge testing comes after it emerged that 6,959 cases of the Indian variant of coronavirus had been confirmed in the UK up to May 26, a rise of 3,535 on the previous week.
Public Health England (PHE) said the local areas most affected by the Indian variant of coronavirus continued to be Bolton, Bedford and Blackburn with Darwen, which have seen 1,354, 366 and 361 confirmed cases respectively.
Seven further areas in England have more than 100 confirmed cases of the Indian variant: Leicester (197), Sefton (175), Nottingham (158), Wigan (113), Central Bedfordshire (109), Manchester (105) and Hillingdon (102), PHE added.