Extra COVID testing will be carried out in parts of Wandsworth, southwest London, after cases of the South African variant were identified.
The Department of Health and Social Care said additional testing and genomic sequencing is being deployed within the SW11 and SW15 postcodes.
Enhanced contact tracing will be used for individuals testing positive with a variant of concern.
Residents living within the targeted areas are strongly encouraged to take a COVID-19 test when offered, whether they are showing symptoms or not.
People with symptoms should book a free test online or by phone so they can get tested at a testing site or have a testing kit sent to them at home.