Britain's government reported 53,135 new cases of COVID-19 on Tuesday (29), the highest number since mass testing started in mid-2020 and up sharply from the previous record of 41,385 set on Monday.
The number of new deaths recorded within 28 days of a positive COVID test also rose to 414 from Monday's 357, taking the total since the start of the pandemic to 71,567.
Britain vies with Italy for Europe's highest death toll from the disease and is now battling a new variant of COVID which scientists say can spread more rapidly.
"We are continuing to see unprecedented levels of COVID-19 infection across the UK, which is of extreme concern particularly as our hospitals are at their most vulnerable," said Susan Hopkins, a senior medical advisor to Public Health England.
Hopkins added that some of the daily rise in cases reflected reporting delays due to Christmas, but the figures were "largely a reflection of a real increase".
Health minister Matt Hancock will give an update on regional coronavirus restrictions on Wednesday.
Earlier on Tuesday a leading epidemiologist who advises the government, Andrew Hayward, warned that Britain was heading for "catastrophe" over the coming weeks if it did not take tougher action against the more infectious variant of the disease.
Just under half of England's population, centred around London and neighbouring regions, is currently under the tightest form of COVID restriction. Under these rules non-essential shops and most other businesses are closed to the public, and almost all face-to-face socialising is prohibited.
However in most of Britain rules were relaxed to allow families to meet on Christmas Day, which many health officials said risked causing a spike in COVID infections.
