The European Union is funding an experiment to secure its borders using swarms of drones patrolling land, sea and air.

The £7.7m multiyear project, known as Roborder, relies on a host of unmanned vehicles - ranging from large submersibles to tiny flying quadcopters - to detect and identify illegal cross-border criminals, from smugglers to people traffickers.

The drones will be equipped with a sophisticated array of sensors to locate and film potentially illegal activity, but will not be armed or authorised to intercept or interdict suspects. Rather information will be beamed back to a manned control room, from where human teams can be dispatched to conduct arrests.

Nonetheless, project documentation submitted to Horizon 2020, the EU Research and Innovation programme which has provided £7m of funding to Roborder, admits that “a significant body of the work done in the area of unmanned systems and passive radar has so far been motivated and funded by military applications, so the results of this project have the potential to be used back in the defence sector”.

That has led campaigners, such as Noel Sharkey, emeritus professor of robotics and artificial intelligence at Sheffield University and a founder of the International Committee for Robot Arms Control to warn that “it’s only a matter of time before a drone will be able to take action to stop people.” He told The Intercept, which first reported the story, that the project was “a dark step into morally dangerous territory”.