Public Health England said the scale of infections and pressure on hospitals was causing “extreme concern”.
A leading scientific adviser to the UK government said urgent action was needed to prevent a “catastrophe” in the New Year.
There are calls for a delay in the return to school after the Christmas break, to prevent the spread of infections. The armed forces are being drafted in to help with testing in schools.
China on Saturday finished a five-day construction project on a 1,500-room hospital as clusters of COVID-19 spread in Beijing and the surrounding provinces.