A group of intelligence experts have said it is 'only a matter of time' before terrorists launch 'drone attacks' on major sporting events in Europe and the US.

Analysts at the Open Briefing think tank believe terrorists could use a swarm of drones, which are cheap and accessible, to attack crowds of people at an event like the Superbowl.

They believe such an attack could be launched by sleeper cells or lone wolves who have been brainwashed by ISIS or Al Qaeda terrorists.

A group of intelligence experts have said it is 'only a matter of time' before terrorists launch 'drone attacks' on major sporting events in Europe and the US (file photo of ISIS fighters)

Analysts at the Open Briefing think tank believe terrorists could use a swarm of drones, which are cheap and accessible, to attack crowds of people at an event like the Superbowl (pictured)

'ISIS are already using drones in Iraq and Syria for intelligence gathering, quite successfully for battlefield awareness,' the group's chief executive Chris Abbott told the Daily Beast.

'They are in direct competition now with al Qaeda and are desperate to launch a mass casualty attack on Western targets.'

He added that given ISIS's 'sophisticated' use of propaganda, the drones could even be fitted with cameras to film the attacks taking place.

Abbott's team looked at the large number of small 'off the shelf' drones on the market and analysed their potential threat.

He said there was no single counter measure that could prevent such attacks, and the defence starts with regulating who can own a drone.

He added: 'Unfortunately if you have to resort to shooting them out of the sky in an urban environment or at a packed stadium the risk of collateral damage is very high.'

Abbott said even a small drone, capable of carrying up to 10kg of explosives or a suicide vest, could be lethal if directed at a high profile target such as a politician.

Experts believe a drone attack could be launched by sleeper cells or lone wolves who have been brainwashed by ISIS or Al Qaeda terrorists (file photo of a drone)

They claimed terrorists' may even fit cameras on the drone so they can film the attack taking place (file photo of ISIS terrorists)

In 2013, a drone operated by the German Pirate Party landed near German Chancellor Angela Merkel as she addressed a supporters' rally in Dresden.

And last April, a drone carrying radioactive sand from the Fukishima nuclear plant landed on top of the Japanese prime minister's offices in Tokyo.

Last April a small drone carrying a sample of radioactive sand from the Fukishima nuclear plant landed on the roof of the Japanese prime minister's offices in Tokyo.