England's "very high" Covid infection level is a "growing concern" as the NHS struggles to cope with rising patient numbers, a health official has said.
On Monday, a record 41,385 Covid cases and 357 deaths were reported in the UK.
NHS England said the number of people being treated for the virus in hospital is now 20,426, which is higher than the previous peak of about 19,000 in April.
Health officials in Wales and Scotland have also said they are at risk of becoming overwhelmed.
Monday's figure for new cases is the highest daily number reported by the UK government, and the first time the daily total has surpassed 40,000.
It is thought the infection rate was much higher during the first peak in April, but testing capacity was too limited to detect the true number.
Some data over the Christmas period is incomplete, as a result of certain services being paused.
BBC health editor Hugh Pym said Monday's figure included some infections where reporting was delayed, but that officials did not deny there had been a significant increase in infections.