Drones spotted flying over English football grounds are being investigated by the Civil Aviation Authority (CAA).
The remote-controlled aircraft flew over stadiums recently in Nottingham and Derby as games were under way.
The flights could be in breach of legislation that states they must not be flown within 150m of built-up areas.
A drone enthusiast, who did not want to be named, filmed videos over cities but said he believed he had followed the rules.
It comes after the halting of the Euro 2016 qualifier in the Serbian capital Belgrade on Tuesday night, when a drone carrying an Albanian flag was flown over the stadium, sparking a brawl.
The small, unmanned aircraft have become cheaper and more widely-available in recent years, prompting concerns about public safety.
Supt Mark Holland, from Nottinghamshire Police, said: “We’ve had a couple of incidents here in Nottingham where we’ve had drones flying over a Nottingham Forest game and also a Notts County match.
“Clearly we are concerned around public safety. These drones can weigh quite a number of kilos and once it’s out of sight… it could cause some problems.”
Jonathan Nicholson, a spokesman for the CAA, said: “The rules that apply in the UK apply to everyone. It doesn’t matter if you are going to fly over the football ground. a park or anywhere else… you should not fly any kind of drone within 150m of a built-up area.”
He added: “The police [in Nottingham] did intercept somebody and we are working with Nottinghamshire Police in an ongoing investigation.”
Further legislation forbids flying within 150m of a large gathering of people in open spaces, the CAA said.
But one man, who posts videos to his YouTube Channel PV2+ Adventures, said he did not believe he had broken any rules.
The Nottingham man, who flies drones as a hobby, said he practised for many months in empty spaces before flying in cities.
“I believe I am within the rules. People can be negative because it is something new and they don’t understand it.
“I think the rules say you have to be more than 50m from built-up areas and that’s at take off. As long as you keep it within sight it’s fine.
“I’m not saying problems can’t happen but they are down to poor piloting. It’s only like people driving a car badly.”
He added that he stopped flying at the Nottingham Forest game after police spoke to him but said there was another drone there that night.