Britain's chief medical officers (CMOs) have recommended moving the country's COVID-19 alert level from level 3 to level 4, according to a joint statement released on Monday.
Level 4 means COVID-19 epidemic is in general circulation, transmission is high or rising exponentially.
"The CMOs for England, Scotland, Wales and Northern Ireland have reviewed the evidence and recommend all 4 nations of the UK should move to level 4," said the statement, reports Xinhua.
The recommendation was tabled at a time when countries such as Britain, China, Russia and the United States are racing against time to develop coronavirus vaccines.
After a period of lower COVID-19 cases and deaths, the number of cases are "now rising rapidly and probably exponentially in significant parts of all 4 nations", said the CMOs.
Britain recorded another 4,368 COVID-19 cases overnight on Monday, bringing the total to 398,625, according to latest official figures.
"If we are to avoid significant excess deaths and exceptional pressure in the NHS (National Health Service) and other health services over the autumn and winter, everyone has to follow the social distancing guidance, wear face coverings correctly and wash their hands regularly," said the CMOs.