The number of daily UK cases of coronavirus has risen to 1,522 in the past 24 hours – the highest tally since mid-June.
This is still much lower than the 5,000 new cases a day in April, at the peak of the epidemic.
Cases have been rising across Europe and began edging up again in the UK in July, after falling in June.
A number of areas have seen a spike in infections, with Birmingham and Northampton the latest places affected.
And experts suspect a relatively small number of areas in the UK are responsible for an increase in new cases.
Testing has also increased over recent weeks and this means more people with the virus are being detected.
The last weekly testing of people in thousands of private households, by the Office for National Statistics (ONS), seen as the most accurate picture of new infections, suggested cases were levelling off.
New weekly ONS figures will be released on Friday.
Meanwhile, the numbers of people admitted to hospital and dying from Covid-19 are on a downward trend.
As of Thursday, the government reported 41,477 people had died in the UK within 28 days of testing positive for coronavirus – a rise of 12 on the previous day.
Separate figures published by the ONS show there have now been 57,200 deaths registered in the UK where Covid-19 was mentioned on the death certificate.