The European Commission has adopted new rules for drones, to harmonise regulations across the 28 members of the EU and improve certainty for business.

The rules require drone operators to register with national authorities by 2020. Member states will be able to define no-fly zones where drones will not be allowed to enter. These can include airports, airfields or city centres.

The move is part of a response to incidents involving drones and fears about the safety risk they pose. In December, hundreds of flights were delayed at Gatwick Airport in the U.K., near London, following sightings of drones. About 140,000 passengers suffered disruption to their travel plans. The drone operator has still not been identified.

These new rules will apply to drones operated by public authorities or by private individuals. Most of the measures will apply from next year, with some coming into force a year later.

"The EU will now have the most advanced rules worldwide," Violeta Bulc, the EU's transport commissioner, said in a statement. "This will pave the way for safe, secure and green drone flights. It also provides the much-needed clarity for the business sector and for drone innovators Europe-wide."