Madrid airport, Spain's main air hub, was forced to suspend flights for about 30 minutes on Monday because drones were believed to be flying nearby, authorities said.

Drones have previously interrupted flights at other major airports around the world, including Gatwick outside London in December 2018.

"Delays at the airport because of the possible presence of drones nearby," announced Enaire, the public body that manages Spanish airports and controls air traffic.

"Drones are not toys," Enaire said, adding that flying them "near an airport is a serious infraction and sanctions can amount to 90,000 euros" ($99,000).