STOCKHOLM, Sept 29, 2025 (BSS/AFP) - Swedish Prime Minister Ulf Kristersson said Monday Russia was likely behind mysterious drone flights over several Scandinavian airports ahead of an EU summit in Copenhagen.

Drone sightings across Norway and Denmark in particular since September 22 have prompted the closure of several airports.

Speaking to broadcaster TV4, Kristersson said "the likelihood of this being about Russia wanting to send a message to countries supporting Ukraine is quite high" but stressed that "nobody really, really knows"..

He added that "we have confirmation" that drones that entered Polish airspace earlier in September were Russian.

"Everything points to (Russia), but then all countries are cautious about singling out a country if they are not sure. In Poland, we know that's what it was," he said.

Drones were also observed over Danish military sites Saturday night for a second straight day.

Copenhagen is to host an EU summit on Wednesday and Thursday.

To ensure security around the summit, Denmark on Sunday said it was closing airspace to all civilian drone flights until Friday, so that enemy drones would not be confused for legal ones.

A violation can result in a fine or imprisonment for up to two years.

Danish Prime Minister Mette Frederiksen said this week that "there is one main country that poses a threat to Europe's security, and it is Russia".

Moscow said it "firmly rejects" any suggestion of involvement.

The string of drone sightings comes on the heels of drone incursions in Polish and Romanian territory and the violation of Estonian airspace by Russian fighter jets, which raised tensions in light of Russia's ongoing invasion of Ukraine.

NATO has said it has "enhanced vigilance" in the Baltic following the intrusions.