From Monday, any social gathering of more than six people is against the law , with people facing fines of up to £3,200 if they do not abide by the new measure, which applies to both indoor and outdoor settings .
Policing Minister Kit Malthouse said concerned neighbours should ring the non-emergency police phone number to report violations.
He told BBC Radio 4’s Today programme: “We are in discussions about what reporting mechanisms there might be, but there is obviously the non-emergency number that people can ring and report issues they wish to.”
Pressed on whether that would involve reporting a gathering of seven or more in a neighbour’s garden, Mr Malthouse said: “It is open to neighbours to do exactly that through the non-emergency number, and if they are concerned and they do see that kind of thing, then absolutely they should think about it.”
He told Times Radio he had cancelled his own child’s birthday party to avoid breaking the rules.
“You are speaking to a dad who had to cancel his own kid’s birthday party next weekend,” he said. “You cannot meet socially in groups of more than six in England and that includes children.
“While I understand that people will say “They are mixing in school anyway’, this is not about eliminating contact, it’s about limiting contact.”
National Police Chiefs’ Council (NPCC) chairman Martin Hewitt denied that enforcement of the rule of six relies on people “grassing up” their neighbours.
“I think what it relies on is all of us being responsible,” he told BBC Breakfast. “We all have a responsibility to do what we can do, to take the steps that are required to stop the transmission and to abide by regulations so we can prevent this disease moving further through the country.”
Regulations enabling the enforcement of the rule were published late on Sunday night, around 30 minutes before they came into effect.
Mr Hewitt said he accepted that rule changes are “confusing for the public”, adding: “This has been really challenging for policing over six months. We had the initial universal lockdown, we’ve had changes since then, the public need to understand those changes.
“We work with all our partners in local authorities, people who are running shops, people who are running other hospitality areas, we are part of the group that are trying to explain to members of the public what the rules are and encouraging people to comply with them.”
The new measures follows a spike in coronavirus cases across the UK , with more than 3,000 cases recorded for the third day in a row on Sunday – the first time since May that cases were above 3,000 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.
Apart from limited exemptions including work and education, police will be able to disperse gatherings of more than six people and issue fines ranging from £100 to £3,200.
Deputy Assistant Commissioner Matt Twist, who leads the Metropolitan Police’s response to coronavirus, said officers will be deployed in every borough to patrol public spaces and respond swiftly to incidents where groups gather in large numbers.
“Where people just won’t listen, and are putting everyone at risk, we absolutely will take enforcement action,” he said.
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 participating in gatherings of more than 30 and the current guidance on allowing two households to meet indoors
Meanwhile, a survey suggests a second peak is the number one concern among medics who want to avoid a return to the “horror and tragedy” of the pandemic’s early days.
The British Medical Association (BMA) poll found that 86 per cent of more than 8,000 doctors and medical students in England said a second peak is likely or very likely in the next six months.
Officials will be hoping the warm and sunny weather forecast for Monday does not encourage people to gather in groups in outdoor spaces.
Temperatures as high as 29C (84F) are expected in some parts, according to the Met Office.
The Government said that, as of 9am on Sunday, there had been a further 3,330 lab-confirmed cases of coronavirus in the UK.
Tough new Covid-19 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.
According to Government advisers, the last time R was above one was in early March.