On Monday evening, between two to three large drones were reported flying in the area around Copenhagen Airport, according to authorities.
Take-offs and landings at the airport were suspended for approximately four hours.
In a statement, the airport warned of ongoing delays and cancellations, and urged passengers to check the status of their flight with their airlines.
Asked by reporters if the drones were of Russian origin, Mr Hansen said he could not confirm or deny this.
Later, Ukrainian President Volodymyr Zelensky on social media referenced “Russia’s violation” of Nato airspace in Copenhagen on 22 September, but did not indicate a source for the information.
EU and Nato leaders have not made a public attribution.
Police said there would be another press conference at 07:00 local time (05:00 GMT) on Tuesday 23 September.