Crime-fighting technology is getting more sophisticated and rightly so. The police need to be equipped for the 21st century. In Britain we’ve already got the world’s biggest DNA database. By next year the state will have access to the genetic data of 4.25m people: one British-based person in 14. Hundreds of thousands of those on the database will never have been charged with a crime.

Police forces are experimenting with cameras in police helmets. The footage will be stored on police computers, along with the footage from thousands of CCTV cameras and millions of pictures from numberplate recognition cameras used increasingly to check up on motorists.

And now there’s a new spy in the sky. It’s called the Microdrone and it’s a toy-sized remote-control craft that hovers above streets or crowds to film what’s going on beneath.

It has emerged that the Microdrone was used by Staffordshire police to film rock fans at the V Festival last month. What wasn’t revealed was that MW Power, the supplier, has also been in discussions to supply the Microdrone to – according to Alistair Fox, an MW Power spokesman – MI5, the Metropolitan police, and Soca, the Serious Organised Crime Agency.

This means the Microdrone could soon become a common sight. Or maybe not. At only 2ft wide between the tips of its rotors the drones are small enough to be unnoticed by people on the ground when they are flying at 350ft.

The drones contain high-resolution video surveillance equipment and an infrared night vision capability, so even in darkness they give their operators a bird’s-eye view of locations while remaining virtually undetectable.

The worrying thing is, who will get access to this technology? Merseyside police are already employing two of the devices as part of a pilot scheme to watch football crowds and city parks looking for antisocial behaviour.

“We’ve already got interest from half the police forces in the country who want to set up trials as soon as possible,” says Fox, adding that the Microdrone has many applications outside surveillance. West Midlands fire brigade is about to lease a drone, for example, to get a better view of fire and flood scenes and aid rescue attempts; the Environment Agency is considering their use for monitoring of illegal fly tipping and oil spills.

The drones cost about £30,000 or can be leased for £1,000 a month – a fraction of what it costs to put a helicopter into the air. MD Power says it has no plans to license the equipment to individuals or private companies, which hopefully will prevent private security firms from getting their hands on them.

But what about local authorities? Lord help us if the fanatically anticar Richmond borough council in London starts to deploy them against motorists. And where will the surveillance society end? Already there are plans to introduce “smart water” containing a unique DNA code identifier that when sprayed on a suspect will cling to their clothes and skin and allow officers to identify them later.

As long as the Microdrone is a high-tech tool in the fight against crime and terrorism, fine. But if it’s another weapon to be deployed by the growing army of snoopers then we don’t want it.

gear@sunday-times.co.uk

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