Fears of a deadly second wave of coronavirus infections mounted today after official data showed the rate of transmission has risen above the critical level.
The reproduction rate — known as R — is now between 1.0 and 1.2, according to the Government Office for Science.
It marks an increase on last week, when the R rate was between 0.9 and 1.1. The daily growth rate for the UK as a whole is between -1 per cent and 3 per cent, up from between -1 per cent and 2 per cent.
The R rate represents the average number of people that one infected person will pass the virus on to.
Scientists have warned that 1.0 is the crucial cut-off rate, with any figure above this level potentially leading to rapid exponential growth.
However, the figures are driven largely by local outbreaks and experts have said that estimates are less reliable when overall incidence of the virus is low.
It came as new figures showed Covid-19 infections in England have jumped 60 per cent to 3,200 new cases each day.
Prime Minister Boris Johnson this week announced that from Monday social gatherings will be limited to a maximum of six people amid concerns about a resurgence of Covid-19 infections.
But Johnson is facing a revolt by Tory backbenchers, while his Cabinet is reportedly split over the move.
The government today announced tougher lockdown rules for Birmingham, Solihull and Sandwell, while new restrictions have also been introduced in Bolton.