The Independent on Sunday can today reveal that the tiny planes will fly at more than 2,500 feet over the English Channel and Mediterranean beaches as part of a £1bn programme to equip Europe's police forces, customs officers and border patrols with hi-tech surveillance and anti-terrorism equipment.
The aircraft, called unmanned aerial vehicles (UAVs), are already being used by the Belgian government to catch tankers illegally dumping oil in the North Sea. Several ships' captains have already been prosecuted.
The European Commission now wants to use similar drones, which can have a 6-metre wing-span and weigh as little as 195kg, to patrol the Mediterranean coasts and the Balkans where illegal immigrants try to enter the EU. The Russian government is also close to flying drones over its borders.
A senior commission official said: "We're convinced that this is a very good way of using military technologies for non-military purposes."
Alongside the new "spies in the sky", officials in Brussels have launched more than a dozen research projects to develop new technologies for counter-terrorism, policing and border security. They include body scanners that can see through clothing and detect explosive vests, guns or chemical weapons; portable devices that can "see" through walls and detect people moving inside buildings; and tiny radio tags that would be fitted on people inside buildings under surveillance.
However, the research programme, which will start in earnest early next year, has caused alarm among civil liberties groups and MPs. They accuse officials in Brussels of breaking EU law by starting these projects before they had been agreed by MEPs and member states. A new report by the London-based civil rights group Statewatch and the Transnational Institute in Amsterdam claims that Brussels and the European defence companies are desperate to catch up with spending in the US, where President Bush has pledged to spend $1bn (£530m) a year on "homeland security".
Ben Hayes, the author of the report, said: "Everyone agrees with more money for the police and security services to combat terrorism, but the danger is that EU policy is increasingly skewed towards a particular brand of 'security', based on military, police and corporate interests."
A British-built "spy in the sky" is already in service with the US Immigration Department, patrolling the Mexican border where millions of illegal workers cross into the US every year.