Denmark has been rocked by a fresh round of drone incursions - just days after Copenhagen and Oslo airports were struck by the same problem.

Multiple flights were impacted at Aalborg Airport, a spokesman said, including two SAS planes, one Norwegian Airlines plane and one KLM flight.

Police went onto confirm that drones were seen near the airport - and its airspace has been closed.

"Police are present and investigating further," a statement added.

The force are currently unsure whether the drones spotting in the airport's airspace are the same ones that caused Copenhagen Airport to close

The force added that it was unsure whether the drones spotted in the airport's airspace are similar to those that caused Copenhagen Airport to close earlier this week.

The Danish Government later linked the flying objects to a host of recent incursions by Russian drones seen across Europe.

It added that Monday's incident was the most serious attack on the country's infrastructure to date.

Airspace over Oslo Airport was closed for three hours after drones were sighted on the same evening.

Danish Prime Minister Mette Frederiksen said she 'cannot deny' that the aircraft were of Russian origin

Danish Prime Minister Mette Frederiksen later said she "cannot deny" that the aircraft were of Russian origin.

"What we saw last night is the most serious attack on Danish critical infrastructure to date," Frederiksen said on Tuesday.

Although investigators have not officially identified the perpetrators behind the incursions, experts have suggested it may be part of a test to see how European countries manage their critical infrastructure.

Jukka Savolainen, of the European Centre of Excellence for Countering Hybrid Threats, said: "First is to test how the method works. In this case, it leads to closing down airports.

"The second testing point is our reaction."

The Danish Armed Forces have also been impacted due to Aalborg being used as a military base

Danish national police said the drones seen breaching Aalborg Airport's airspace follow a similar pattern to those sighted in Copenhagen - and appear to have their lights switched on.

The force added that Danish Armed Forces have also been impacted due to Aalborg being used as a military base.

Authorities also confirmed they have received reports of further drone sightings around the country.

Local reports also indicate drones were seen near Esbjerg, Sønderborg and Skrydstrup airports.

Eurocontrol, which oversees air traffic control across the continent, said Aalborg Airport's airspace would be shut until 4am on Thursday.

The incident comes after a wave of cyber-attacks caused chaos at a number of key European airports.

On Sunday, Brussels, Berlin and London's Heathrow Airport saw flight cancellations and huge delays after the service provider for boardings systems was targeted.

On Wednesday, a man in his 40s was arrested in connection to the attacks, but has since been released on conditional bail.