The Government has said that a law change will ban larger groups meeting anywhere socially indoors or outdoors, including in hospitality settings such as restaurants and pubs.
It will be enforced through a £100 fine if people fail to comply, doubling on each offence up to a maximum of £3,200.
The BBC's political correspondent Nick Eardley has pointed out that pubs and restaurants will still be allowed to have more than six customers inside, but that the groups of six would have to be socially distant from each other.
However, the changes are likely to put more pressure on hospitality businesses to check the make-up of larger parties when taking bookings and receiving guests.
Reports say that Prime Minister Boris Johnson is expected to hold a Downing Street press conference later today (9 September) to outline the new restrictions.
As lockdown measures in England have eased over the summer, guidance has allowed gatherings of up to six people from different households outdoors; or two households of any size, indoors or outdoors.
Until now, though, the police have had no powers to stop them unless they exceeded 30.
The changes have reportedly been designed to strengthen rules and aid police enforcement, and will apply across all of England and in both private and public spaces, including parks, pubs and restaurants.
Exemptions to the new rules are understood to include households or support bubbles are larger than six people; gatherings that are for work or education purposes; and weddings, funerals, or organised team sports.
A full list of exemptions is due to be published before the law changes.
“Just as we were starting to build a tiny bit of momentum, this announcement is another kick in the teeth for the hospitality sector. This will undermine consumer confidence and set the entire sector back even further. It's incredibly difficult to understand this move in the context of the current data, especially in London where death and hospitalisation rates are low," says Grind founder David Abrahamovitch.
"The furlough scheme is coming to an end, and trading through the important Christmas period is starting to feel less and less likely. It's hard to foresee a situation that doesn't result in a bloodbath and closures in the industry later this year and continuing into early 2021."
The news follows yesterday's (8 September) announcement that hospitality venues in Bolton will be restricted to offering takeaway-only with immediate effect under new local lockdown measures brought in following a 'significant rise' in Coronavirus cases in the town.