People face fines of up to STG3200 ($A5600) if they do not abide by the new measure, which applies to both indoor and outdoor settings and follows a rapid increase in the number of daily positive cases.
More than 3000 COVID-19 cases were recorded in the UK for the third day in a row on Sunday – the first time since May that cases were above 3000 on three consecutive days.
The new law comes amid concerns about an increase in cases in care homes and growing criticism of the NHS Test and Trace system.
Aside from limited exemptions including work and education, police will be able to disperse gatherings of more than six people and issue fines ranging from STG100 to STG3200.
Home Secretary Priti Patel said the recent rise in cases “makes it clear that more needs to be done to stop the spread of this disease”.
The rule applies across England and replaces the existing ban on taking part in gatherings of more than 30 and the current guidance on allowing two households to meet indoors.
As of Sunday morning, there had been a further 3330 lab-confirmed cases of coronavirus in the UK.
Tough new lockdown measures were announced for parts of the UK on Friday as cases continued to rise and as the R number – the reproduction number of coronavirus transmission – climbed above one.
It came as the World Health Organisation reported a record one-day increase in global coronavirus cases, with the total rising by 307,930 in 24 hours.
The biggest increases were from India, the United States and Brazil, according to the agency’s website on Sunday.
Deaths rose by 5537 to a total of 917,417.
India reported 94,372 new cases followed by the United States with 45,523 new infections and Brazil with 43,718.
Both the United States and India each reported more than 1000 new deaths and Brazil reported 874 lives lost in the past 24 hours.
The previous WHO record for new cases was 306,857 on September 6. The agency reported a record 12,430 deaths on April 17.
India leads the world in new cases reported each day and set a global record last week with 97,570 cases reported in a single day, according to a Reuters tally.
In some parts of India, medical oxygen is becoming hard to find as total cases exceed 4.75 million.
Only the United States has recorded more cases at 6.5 million.
COVID-19 infections are still rising in 58 countries, including surges in Argentina, Indonesia, Morocco, Spain and Ukraine, according to a Reuters analysis.
New cases are falling in the United States and are down about 44 per cent from a peak of more than 77,000 new cases reported on July 16.
Cases in Brazil are also trending downward.
Make your contribution to independent news
A donation of any size to InDaily goes directly to helping our journalists uncover the facts. South Australia needs more than one voice to guide it forward, and we’d truly appreciate your contribution. Please click below to donate to InDaily.