The police have set themselves up for a conflict with ministers by insisting that they will not enforce mask-wearing in supermarkets amid growing calls for tougher Covid measures including a crackdown on the number of people in workplaces. Sources said the government was actively considering telling people to wear masks outdoors as the NHS faces its “most dangerous” point. A further 4,193 people were reported to have gone to hospital with coronavirus on Monday, bringing the current total to 32,294. A ban on people in England walking or exercising with anyone from outside their household is also on the table, with sources saying it was “under active consideration”. Ministers have been urged by trade unions to focus on underlining the need for home working as figures show that traffic on the tube in London – often used by commuters – is more than three times higher than in the first lockdown. The government is keen to intensify efforts to keep contact limited in supermarkets amid concern about infection rates linked to stores. Stores have said they will require help from police if ministers want to increase enforcement of rules such as mask-wearing and social distancing. On Monday, Morrisons announced that shoppers who refuse to wear a mask without a medical exemption will be told to leave stores. Sainsbury’s followed suit, saying it would be posting trained security guards at shop entrances, rather than shop staff, to challenge any customers not wearing a mask or shopping in groups. The supermarket said it had also significantly reduced the number of customers allowed into stores at any one time. It is understood that Morrisons is prepared to call in police as a last resort if customers do not comply with requests to wear a mask. At Monday’s Downing Street briefing, the health secretary, Matt Hancock, cranked up pressure on law enforcement and supermarkets, saying stronger action was needed, and applauded Morrisons. “That’s the right approach, and I want to see all parts of society playing their part in this,” he said. “Stronger enforcement is necessary, and I’m delighted that the police are stepping up their enforcement. But it isn’t just about the government and the rules we set, or the police and the work that they do. It’s about how everybody behaves.” But multiple law enforcement sources said it would be impossible for officers to police supermarkets and insisted forces needed greater clarity about how the rules should be imposed. On Monday Derbyshire police said it had withdrawn controversial £200 fines handed to two women who drove five miles from their home to meet for a walk. Apologising, the force said it had been “working hard to understand the ever-changing guidance and legislation”. Asked about enforcing rules in supermarkets, one senior police leader said “we won’t be doing that”, adding: “Do people really want the police telling you: ‘that’s not above your nose’? There are no extra officers. Everything else [crime] is still happening. Where is the greater risk: do you put two people in a supermarket not wearing masks before a woman suffering domestic violence? “You need clearer, consistent messaging, not new rules and more enforcement.” A chief constable said: “I do not think we need additional powers; I need additional clarity about the exceptions, about how far people can travel.” Another senior police source added: “The government wants to see more enforcement but that will not regulate behaviour. There is no way the 40,000 officers you can deploy can enforce regulations on 65 million people if they do not want to follow.” Police are being quicker to issue fines to those they believe will not comply with the rules but are wedded to an approach of trying to encourage people. Police in England and Wales have issued around 30,000 penalty notices, while counterparts in France have issued over 1 million. A government source insisted there were no imminent changes to the rules planned and said the emphasis was on messaging and enforcement, urging people to stay within existing rules rather than any tighter legal restrictions. However, it is understood discussions in government took place over the weekend and on Monday about returning to some of the rules of the first lockdown in March, which limited people to one form of outside exercise a day either alone or with people from their household. Hancock has said he would not remove the right for people to access “support bubbles” where people can form tightly restricted bubbles with one other household if they live alone or if family members provide childcare. “I can rule out removing the bubbles that we have in place,” he said. “Childcare bubbles and support bubbles are very important, and we’re going to keep them.” Hancock declined to say what extra rules might be brought in and implored people to “act like you have the virus”. He said: “I know there’s been speculation about more restrictions. We don’t rule out taking more action if it’s needed but it’s your actions now that can make a difference.” Concerns have been raised by trade unions about home working, with statistics suggesting many more people are in the workplace compared with the March lockdown. Figures from Transport for London suggested there are four times the number of tube passengers compared with the first lockdown, when there was just 4% of normal demand in mid-April. On Monday, demand on buses was at 29% compared to 18% in mid-April. Unite’s general secretary, Len McCluskey, said the government must instruct employers to use the furlough scheme to keep employees out of the workplace and enforce the stay at home message, but he said support from the Treasury was lacking. “Time and again, ministers have been told that unless employers are instructed to use the furlough scheme, too many will demand that workers come to work, therefore undermining an essential public health message,” he said. “And unless the low paid and insecure are paid enough to stay at home then they cannot do so.” The government has also been urged to emphasise the need for civil servants to stay at home. Lucille Thirlby, assistant general secretary of the FDA, which represents civil servants, said: “The civil service should be leading the example and ensuring that staff do not attend the workplace and work from home, unless their role is of immediate critical delivery or importance.” The Labour leader, Keir Starmer, said harsher restrictions should be considered within 24 hours and highlighted estate agents and house viewings as one area where rules could be tightened, as well as nurseries. On Monday, Wales’s health minister, Vaughan Gething, said he believed it would be “easier” not to remove a face covering when moving between essential shops. A government spokesperson said: “We are incredibly grateful for the work the police are doing to explain and enforce the current coronavirus restrictions. “As they have throughout the pandemic, the police will support enforcement of the regulations and will attend retail settings as necessary to respond to reports of crime and public order offences. “We are at a critical point in this pandemic and all of us need to be doing the right thing. People should only be leaving home if it is essential for them to do so and they must follow the rules when they do.”