Surge testing will take place in two more London boroughs after cases of the Covid-19 South African variant were found in both areas.
Residents in "targeted areas" within the SE16 postcode in Southwark and N3 postcode in Barnet are being urged to get tested.
All identified cases are isolating or have completed their isolation.
Testing has begun in the Rotherhithe ward of Southwark and Covid-19 tests are being delivered to properties in the immediate area.
Residents can also collect and drop off a Home Testing kit from Canada Water Library Theatre between 09:00 and 17:00 BST every day.
A temporary testing site is being opened at Deal Porter Square, next to the library.
Testing will begin at Finchley Central Underground Station car park on Thursday after one confirmed case was identified in N3.
Dr Tamara Djuretic, Barnet's Director of Public Health, said: "There is no evidence at present that they have passed the infection further."
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Case totals for some local authorities in England fell on Friday due to a change in the way the government reports the results of lateral flow tests.
On Wednesday, the Mayor of London, Sadiq Khan, said: "Additional testing will be taking place in a targeted areas within SE16 in Southwark after a confirmed case of the Covid-19 variant first discovered in South Africa was found."
He said it was "vital" that those being asked to take a test in the area do so.
"This testing is essential to help monitor and suppress the spread of the virus, so I urge everyone contacted in this area and all those living and working in Wandsworth and in Lambeth to book their tests as soon as possible," the mayor added.
Meanwhile, some people have taken to Twitter to complain about long queues at test sites in Lambeth on Wednesday.
Isobel Knight said: "I waited in line for over an hour this morning for the Lambeth surge testing.... If I didn't have Covid before, I probably do now."
So I waited in line for over an hour this morning for the Lambeth surge testing... only one pen for this whole queue? If I didn’t have covid before, I probably do now... pic.twitter.com/wmuBoUpEL0— Isobel Knight (@IsobelSylviaAnn) April 14, 2021
Beth Eyre said: "I queued for two hours this morning and still no test as had to leave the queue to go to work."
@lambeth_council if you’re going to ask the entire borough to test for Covid, increase the testing capacity. Queued for 2 hours this morning and still no test as had to leave the queue to go to work... pic.twitter.com/qTEqYW3qj7— Beth (@beth_eyre) April 14, 2021
A Lambeth Council spokesperson said it has increased capacity to ensure queues are manageable.
"We have eight testing sites available for Lambeth residents with more mobile testing units being added, as well as sites open in neighbouring Wandsworth they can use," the spokesperson said.
"These will remain open for a fortnight. Tests are also available by post."
From Thursday 15 April, additional testing sites will be available in Wandsworth, including Putney Leisure Centre and 23 pharmacies.
Surge testing was previously carried out in three postcode areas of Lambeth in February after a case of the South African variant was discovered.
In March, intensive testing was put in place in three areas of Wandsworth borough following a small number of cases.