Covid-19 cases in the capital have been “steadily increasing” for the last few weeks and residents must make a “continued conscious effort to consider our movements and behavior,” Kevin Fenton, London regional director for Public Health England, said in an emailed statement.

The warning comes after Boris Johnson’s chief scientific adviser warned the pandemic is not under control and the prime minister said his government will not hesitate to impose additional restrictions if necessary to contain the virus.

In the House of Commons on Thursday, Health Secretary Matt Hancock announced new rules for large areas of northern England.

Residents in the Liverpool region, as well as Warrington, Hartlepool and Middlesbrough, will be banned by law from meeting other households in settings such as pubs and restaurants. Hancock also warned against “all social mixing between households,” advised residents not to attend sporting events and to only visit care homes in “exceptional circumstances.”

Hancock told members of Parliament that, while an Imperial College London study shows the virus reproduction rate may now be falling across the country, infections are “highly localized” and rising fast in some areas.

In London, Mayor Sadiq Khan has been calling for tighter restrictions as hospital admissions rise again in a new wave of infections.

“Londoners still hold the key to reducing infection rates and lessening the impact of any second wave by making a continued conscious effort to consider our movements and behavior,” Fenton said in the statement.