"The Armed Forces can confirm that drones have been observed at several of the Armed Forces' locations during the night. Several capacities were deployed," the military said in a statement.

It provided no other details about the incidents or the military's response.

Danish media reported that no airports had been closed overnight.

Mysterious drone sightings across Denmark and Norway since September 22 have prompted the closure of several airports, with Denmark hinting at possible Russian involvement.

On Saturday, Denmark's military said unidentified drones had been observed over "several military sites" overnight Friday to Saturday, but refused to disclose any other details.

Police did confirm that "one to two drones" had been observed on Friday evening near and over the Karup military base, the country's biggest base which houses all of the armed forces' helicopters, airspace surveillance, flight school and support functions.

NATO has "enhanced vigilance" in the Baltic following the intrusions, a spokesperson for the defence alliance said.

The reinforced measures "include multiple intelligence, surveillance and reconnaissance platforms and at least one air-defence frigate" in the region to the west of Russia, alliance spokesman Martin O'Donnell told a press conference overnight Saturday to Sunday.

Copenhagen is to host a European Union summit gathering heads of government on Wednesday and Thursday.