New social distancing marshals are set to be appointed to make sure people stick to the rules.
Boris Johnson tonight announced the measure, which has been put in place after a surge in new cases.
It comes as the number of people allowed to meet indoors or outdoors was slashed to just six – but can be from up to six households.
Mr Johnson said in a televised Downing Street briefing: “The government will support Local Authorities and police forces to respond to breaches of Covid-19 Secure guidelines.
“We will launch a register of newly qualified and recently retired Environmental Health Officers (EHOs) so that Local Authorities can recruit more quickly and fill any gaps.
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“In addition, we will introduce Covid-19 Secure Marshals to help local authorities support social distancing in towns and city centres.”
The government has placed a limit on the number of people who can meet indoors and outdoors to six.
The Prime Minister said he is “sorry” that two whole households will no longer be able to meet if their total exceeds six people.
He said: “This rule of six will of course throw up difficult cases, for example two whole households will no longer be able to meet if they would together exceed the limit of six people and I’m sorry about that, and I wish that we did not have to take this step.
“But as your Prime Minister, I must do what is necessary to stop the spread of the virus and to save lives. And of course we will keep the rule of six under constant review and only keep it in place as long as is necessary.”
Mr Johnson said that he has tasked the Cabinet with increasing enforcement of the rules, adding: “In future, premises where people meet socially will be legally required to request the contact details of a member of every party, record and retain these details for 21 days and provide them to NHS Test and Trace, without delay, when required.”
England’s Chief Medical Officer Chris Whitty said Britain’s numbers were following a similar pattern to that seen in France four weeks ago, and risked continuing to rise sharply as they had done there.
He cited Belgium as an example of a country that had seen a similar increase in cases but had managed to reverse the trend through decisive action.