Researchers at the Universitat Autònoma de Barcelona have created a new type of magnetic cloak which shields objects from magnetic fields – at the same time that it prevents any internal magnetic fields from leaking out.

Fox News reports that this “antimagnet” could be used to protect a ship’s hulls from mines that detonate when a magnetic field is detected, or allow patients with pacemakers or cochlear implants to use medical equipment.

The researchers admit, though, that the discovery could also be used by criminals to evade security systems in airports and shops. “It is conceivable that they could be used for reducing the magnetic signature of forbidden objects, with the consequent threat to security,” Sanchez told Fox News. “For these reasons, the research could be taken into account by security officials in order to design safer detection systems and protocols.”

The researchers’ study was published 23 September in the New Journal of Physics.