Police chiefs are drawing up new guidance warning forces not to overreach their lockdown enforcement powers after withering criticism of controversial tactics to stop the spread of coronavirus, the Guardian has learned.

The intervention comes amid growing concern that some forces are going beyond their legal powers to stop the spread of Covid-19, with one issuing a summons to a household for shopping for non-essential items and another telling locals that exercise was “limited to an hour a day”.

On Monday, former supreme court justice Lord Sumption said that excessive measures were in danger of turning Britain into a “police state”, singling out Derbyshire police – which deployed drones and dyed the Blue Lagoon near Buxton black to make it less appealing – for “trying to shame people in using their undoubted right to take exercise in the country and wrecking beauty spots in the fells”.

The Guardian has learned that the National Police Chiefs Council (NPCC) and College of Policing are rushing through guidance reminding officers that despite politicians’ warnings they cannot bar people from going for a run or a drive.

It will state that while certain actions such as driving to exercise may be unwise, they are not prohibited by the emergency powers, according to sources with knowledge of detailed discussions. It is also expected to conclude the law does not restrict people to exercising outside only once a day.

The Guardian understands that the NPCC chair, Martin Hewitt, wrote to police chiefs across the forces in England and Wales over the weekend about the need for greater consistency in the application of emergency powers.

Senior police commanders are understood to have been concerned over how the unprecedented powers were being implemented in their first few days by some forces, with Lancashire police issuing 123 enforcement notices since Thursday and Bedfordshire police issuing none.

The guidance contrasts with local police actions that have ranged from Derbyshire Police filming dogwalkers in the Peak District with a drone to officers telling a shop to stop selling Easter eggs.

Speaking to the BBC, Sumption attacked the behaviour of police and singled out the Derbyshire force.

“The behaviour of the Derbyshire police in trying to shame people in using their undoubted right to take exercise in the country and wrecking beauty spots in the fells so people don’t want to go there is frankly disgraceful,” he said.

“This is what a police state is like, it is a state in which a government can issue orders or express preferences with no legal authority and the police will enforce ministers’ wishes.” He said that the force had “shamed our policing traditions”.

New legislation was introduced and rushed through parliament to become law on Thursday in a bid to enforce physical distancing and slow the spread and death toll from Covid-19.

Senior police chiefs from larger forces are understood to be concerned about “not turning communities against us”, one source with knowledge of discussions said.

Asked on the BBC’s Newsnight about communication from the NPCC, Andy Marsh, chief constable in Avon and Somerset, said: “I had a conversation with other chiefs and Martin Hewitt and we talked about the style of our enforcement and the engagement and explanation that went before and we all agreed that we wanted to see this done with the consent of the public. We’re not going to enforce our way out of this problem.”

He said Hewitt’s message to police chiefs called for common sense and sound judgment and added that the police were “figuring out some of this stuff as we go along”.

On Monday afternoon, the foreign secretary, Dominic Raab, praised the police’s response to the crisis in general but told reporters that “obviously we need some common sense”.

The source of confusion for frontline officers appears to be a gap between what the emergency legislation actually orders and what the government has said it wants people to do.

In his address announcing the lockdown last Monday, Boris Johnson made reference to only exercising once a day – a limitation that is not set out in the law.

There is sympathy in policing for what government is trying to achieve to deal with a national emergency. The unprecedented lockdown measures in the UK are broadly in step with draconian measures countries around the world have or are taking to deal with the pandemic.

Bedfordshire’s chief constable Garry Forsyth told the Guardian that his force had avoided enforcement actions by resolving issues diplomatically. He said that problems enacting the emergency laws were inevitable: “It is difficult to get precision on quick legislation. Of course it could do with more clarity. These are unprecedented times and we have to make the best of what we’ve got.”

Stephen White, police and crime commissioner in Durham, said: “I think policing is confused about what it is being asked to do. Police officers have no power to stop people going to the Lake District. It takes a long time to build up trust and a short time to destroy it.”

The Metropolitan police commissioner, Cressida Dick, whose force covers London, said no checkpoints were being carried out in the capital and her officers were encouraging people to comply: “Already we have had examples of people who simply hadn’t quite heard all the messages – and, only as a very last resort with the current restrictions, using firm direction or even enforcement.

“We’re not doing what you might call road blocks or anything like that,” she told LBC radio station. “Yes, we stop motorists sometimes, we have a conversation with them.”

A spokesperson for the NPCC said: “The vast majority of people are fully complying with the guidance and advice. For the small number who are not we will use enforcement. Given the rapid pace of development forces do not have paperwork specific to the coronavirus regulations.

“Officers are issuing the fines using existing paperwork or statements. All fines issued are legally enforceable and non-payment will result in prosecution.”