Media playback is unsupported on your device Media caption The footage was shot from drones over Anfield, Nottingham's Goose Fair and various parts of London

Drones which could seriously injure or kill are being flown over cities and towns across England, despite laws designed to protect the public.

Dozens of YouTube clips show the aircraft, which can be bought for £300, over populated areas including London, Liverpool and Nottingham.

The Civil Aviation Authority (CAA) prohibits the flying of drones over or within 150m of built-up areas.

But there have been calls for it to do more to raise awareness of the law.

Videos uploaded to YouTube show the remote-controlled aircraft, which have become cheaper in recent years, being flown above bustling areas of London, Liverpool FC's Anfield stadium and towns including Margate and Broadstairs in Kent.

Image copyright PV2+ Adventures

One was also flown directly over Nottingham's Goose Fair while the popular event was taking place.

More videos show drones over football matches and crowds of people in Derby and Stoke.

It comes as new research led by former intelligence chief Sir David Omand found the aircraft were likely to raise significant "safety, security and privacy concerns" over the next 20 years.

'Look like toys'

Chris Wilkinson, director of Upper Cut Productions - a Nottingham-based company which uses drones to film legally, said although the devices had become easier to obtain, in the wrong hands drones could cause serious injury or death.

His colleague, Jordan Brooks said: "They look like toys. For anyone buying one you feel like you're flying a toy 'copter when actually you've got a hazardous helicopter that can come down and injure somebody," he said.

"We've been doing this for 10 years but it's always been a concern of ours that something could happen that could affect the entire industry.

"Our livelihoods could be in danger by the operator of a drone that puts lives at risks but our main concern is the safety of people rather than our business."

Image copyright Honey Worth Image caption There are numerous videos shot from drones over busy parts of London

Image copyright Adam Dark Image caption This footage was recorded during Broadstairs Folk Week in Kent

He said the CAA could be struggling to keep up with the "exponential" growth in the popularity of drones.

"It's almost like they need a specialist enforcement team in place to monitor airspace issues now the air is becoming so populated."

Drones, which can legally weigh up to 20kg, can be ordered online and cost between £300 and £30,000 pounds.

The CAA claimed it had sufficient resources to deal with the growing popularity of drones, and said it would take legal action whenever there was evidence someone had breached regulations set out in the Air Navigation Order.

It also said it would shortly be launching a public information campaign to raise awareness of the rules and regulations.

"Ignorance is not a defence," a spokesman for the organisation said. "The law [on drones] exists and has done for a long time."

The authority has successfully brought two prosecutions this year related to the misuse of drones, he added.

Image copyright Adam Dark Image caption Other clips were filmed over towns and cities across England, including this one of Margate Carnival

Image copyright PV2+ Adventures Image caption One drone was flown over Anfield while people gathered outside

Nigel King, director of Northumberland-based Quest UAV, a manufacturer of fixed-wing drones, said the industry was catching up with the popularity of the devices.

"I think the issue comes from the proliferation of small systems that it's almost impossible to reach so many people," he said.

"It's very easy to spend £300 and go out and have some fun and not realise the law.

"We take it very seriously. We will not entertain certain approaches for sales if we think it's of the wrong nature."

It is unclear whether the YouTube channels hosting the videos are run by the drone pilots themselves, or if the footage was obtained elsewhere.

The BBC has attempted to contact those who posted the clips, but has had no response.

The use of drones has caused controversy recently with the Euro 2016 qualifier in the Serbian capital Belgrade being halted after a drone carrying an Albanian flag was flown over the stadium, sparking a brawl.

And earlier this week, a man from Nottingham was arrested after a drone was flown over the East stand of Manchester City's Etihad Stadium during a match.

Drones and the law

Image copyright Getty Images

Unless CAA permission has been granted the pilot cannot:

Fly over or within 150m (492 ft) of a congested area

Fly over or within 150m (492 ft) of an organised open-air assembly of more than 1,000 persons

Fly within 50m (164 ft) of any vessel, vehicle or structure which is not under the control of the person in charge of the aircraft

Fly within 50m (164 ft) of any person

Source: Civil Aviation Authority