Police chiefs have called for greater clarity on the Government’s new guidelines which restrict people’s movements during the coronavirus pandemic.
Prime minister Boris Johnson said lockdown rules will be enforced by police, and those who fail to adhere could be fined.
Officers will also have the powers to disperse gatherings after a ban on meetings of more than two people apart from those who live together was announced.
However there are questions about how officers will be able to monitor those breaking the rules and what action will be taken.
Currently, there are plans of fines of up to £1,000.
Sir Peter Fahy, former chief constable of Greater Manchester Police, told BBC Breakfast “there is a huge amount of clarification needed”.
Police chiefs have warned of phone lines being swamped with calls after Mr Johsnon’s statements, with people seeking clarity about what is and is not allowed.
Northampton Police Chief Constable Nick Adderley urged the public not to “cripple our phone” lines with inquiries on the PM’s announcement.
Lincolnshire Police warned of an “extremely high volume” of calls, and Humberside Chief Constable Lee Freeman said his force had received “a number of calls” on the subject, but he said he was unable to answer the questions asked.
West Midlands Police Chief Constable Dave Thompson said the force is "already receiving many calls on potential breaches of these arrangements" and said the public could ring 101 with information about large-scale breaches.
Sir Peter said: “There is no way, really, that the police can enforce this using powers; it has got to be because the public hugely support it, that there is peer pressure and there is continuing clarification from Government about the message and going through all the individual scenarios and questions that people will have about what happens in this situation."
He warned that police forces were “already very stretched” and questions would arise about whether officers have powers of arrest if they are tasked with dispersing groups of people.
He added: “So, really, there is no way that this can be achieved through enforcement alone."
Asked how social distancing rules would be enforced by police, Martin Hewitt, chairman of the National Police Chiefs’ Council (NPCC), said it relied on good faith from the public but added: "Ultimately, if people do refuse to abide by the rules then we will need to enforce them.”
However, he said the legislation has not been enacted yet.
The NPCC later said that officers would not be deployed on patrol specifically to police social distancing rules but will “remain patrolling their communities as always”.
Asked whether it was the police’s role to be at railway stations to check if people should be getting on to trains, Mr Hewitt said: “I don’t think we’re at that stage at the moment.
“I think the real point about that is really getting the clarity, I know some other people have said that this morning.
“These are new rules, they are trying to be as clear as they can, but it will take a while, I think, for everybody to get that understanding.”
The Transport Salaried Staffs’ Association has called for police to be deployed at all main London stations to make sure Government instructions are not being flouted, and British Transport Police said officers are on hand to deal with those “clearly disregarding the advice”.
Ken Marsh, chairman of the Metropolitan Police Federation, which represents officers in London, told Sky News the new measures will be a “real challenge” and “very difficult”.
He added: “We will be dealing with it, but I’m not sure we will have the resources to be able to see it through.”
John Apter, national chairman of the Police Federation of England and Wales, had previously told the PA news agency he “cannot imagine” how officers would police social distancing, adding: “I just cannot rationally think how that would work.”
Coronavirus: Everything you need to know