A police force has had a surge in calls from people reporting their neighbours for "going out for a second run".
Government lockdown rules allow people to leave their homes to take one form of exercise a day.
Nick Adderley, from Northamptonshire Police, said the force control room has had "dozens and dozens" of calls about people ignoring the order.
In the coming days, police will be given the powers to fine anyone found to be flouting the law.
Mr Adderley told the Local Democracy Reporting Service his officers will issue penalty notices if necessary, but wanted to educate the public first.
"We are getting calls from people who say 'I think my neighbour is going out on a second run - I want you to come and arrest them'.
"We have had dozens and dozens of these calls."
The force has also been getting reports from people whose neighbours are gathering in their back gardens, Mr Adderley said.
"We won't have police officers crashing through garden fences to check the ID of everyone who is there to see whether they live at the house or whether they should be self-isolating," he added.
"We wouldn't want to discourage people from making us aware, but we have to set expectations. If people think we will be descending on these houses with blue lights, then we won't.
"But be under no illusion, we will be using these powers if necessary."
Supt Ash Tuckley, who leads the control room, said the force did not "want to discourage people from reporting" but stressed the "need to exercise caution".
He said other queries included someone asking if it was illegal not to cough in a tissue, a caller urging police to arrest their neighbour before he drove off, and a man who asked: "My wife doesn't think her job is essential but I do and she's working from home. Is there anything I can do?"
The number of coronavirus deaths in the UK had risen to 465 by Wednesday.