The Danish dual-use Aalborg airport and military base was forced to close last week after unidentified UAVs were spotted nearby

Denmark has called up hundreds of reservists to boost security after mysterious drone sightings near strategic sites, broadcaster TV2 reported on Tuesday.

Air traffic at the dual-use airport and military base at Aalborg was briefly suspended last week after unidentified "drones" were spotted near the runway - the latest in a series of unexplained sightings. Another alleged drone sighting took place at the base hosting Denmark's F-16 and F-35 fighter jets. At Aalborg, despite hours of monitoring, the aircraft were never identified. Days earlier, Copenhagen Airport - the busiest in the Nordic region - was forced to halt flights for hours after similar sightings.

According to TV2, the Danish Armed Forces Command issued a classified order on Sunday calling up part of its reserve force in response to the "complex situation" with drone flights. Several hundred reservists were reportedly summoned, though the exact number is unclear. Denmark has not released reserve figures in recent years, but in 2013 the Main Organization for Reserve Personnel estimated the number at about 3,000. The Defense Command did not respond to TV2's requests for comment.

Denmark imposed a temporary ban on civilian drones after last week's sightings, warning that violations could bring fines or prison terms of up to two years. The ban runs through Friday as the country - which holds the rotating EU presidency - hosts an informal European Council meeting in Copenhagen. The gathering is expected to discuss an EU-wide "drone wall," an initiative that reportedly began last week after alleged airspace violations in Poland, Estonia, and Romania, which were blamed without evidence on Russia.

Moscow has denied involvement in the airspace violations. Speaking at the UN on Saturday, Foreign Minister Sergey Lavrov called the accusations Western "scaremongering."

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"Russia is being accused of almost planning to attack NATO and EU countries. President [Vladimir] Putin has repeatedly debunked these provocations," he said. "We never direct our drones or missiles at states in Europe, members of the EU, or NATO countries." Lavrov added that in past cases when Russia was blamed, "it turned out that it was the Ukrainians who struck."