Belgian defence minister Theo Francken confirmed a number of drones had been spotted over a military training camp in eastern Belgium, adding that he did not know their origin.

"It is certain that several drones were detected by local police forces on the Belgian side and the German side," Francken told RTBF television. An investigation has been launched into the matter.

The drones flew over the Elsenborn military camp, located near the German border, overnight from Thursday to Friday, a spokesperson for the defence minister told AFP. "We are checking the details, looking at what happened, but at this stage we have no further details," she said.

This drone flyover follows several incursions by Russian drones into European airspace. In addition, several drones were spotted flying over Denmark at the end of September, just before two gatherings of European leaders.