Coronavirus: R number rises as UK records nearly 7,000 new COVID-19 infections
Government advisory committee SAGE said it was between 1.3 and 1.6 - up from between 1.2 and 1.5 last week.
In England, the R number is highest in London and the North East and Yorkshire, with both regions having figures between 1.2 and 1.6.
It's lowest in the East of England - between 1.0 and 1.3.
It comes as daily figures for new infections remained roughly the same as yesterday, with 6,968 new cases reported on Friday, compared with 6,914 on Thursday and 6,025 this time last week.
The number of deaths was 66, up from 59 on Thursday and 35 this time last week. It takes the total to 42,268.
There were 2,376 COVID-19 patients in hospital - up 100 on Thursday. The number of admissions was the same as the day before - 323.
The reproduction rate indicates the average number of people each person with coronavirus goes on to infect.
So an R number of between 1.3 and 1.6 means on average every 10 people with COVID-19 will infect between 13 and 16 others.
If the reproduction rate is above one, it means the number of cases will increase exponentially. But if it is below one, the disease will eventually peter out.
The number of new coronavirus cases in the UK is increasing by between 5% and 9% every day, the latest data also reveal.
Today's figures represent transmission over the past few weeks rather than a current snapshot, due to the delay between someone being infected, having symptoms and needing healthcare.
But "this week's estimates are reliable," SAGE said on its website, and "there is widespread growth of the epidemic across the country".
It comes after an Office for National Statistics (ONS) report was published that suggests that the recent sharp rise in cases in England are "levelling off".
New cases were around 8,400 per day for the week 24 September - down from around 9,600 per day during the previous week, according to ONS data.
"There is some limited evidence that the incidence rate may be levelling off following steep increases during August and September," the agency said.
"However the wide credible intervals mean it is too early to say," it added.
The ONS report only covers people who tested positive outside hospital and care homes.
