Denmark has accused a Russian warship of firing two emergency flares at one of its helicopters while it was tracking the vessel in the Baltic Sea.

The Danish government has summoned the Russian ambassador over the incident, which it said happened during a “routine” monitoring operation on Monday.

Prime Minister Mette Frederiksen branded the Russian action “reckless” and said it was designed to “intimidate and divide”.

Moscow has not commented on the incident.

It came on the same day Nato forces shot down a drone over Lithuania in the latest security scare on the alliance’s eastern flank, where tensions remain high during Russia’s full-scale invasion of Ukraine.

In a statement detailing the incident in the Baltic Sea, the Danish armed forces said: “One of the air force’s Fennec helicopters was today fired at with flares during a routine photographic operation of a Russian frigate, which was located in international waters off Gedser.”

Of the two flares fired at the helicopter, one passed close to it, the statement added.

The Danish foreign ministry described the incident as “completely unacceptable”.

Danish Foreign Minister Lars Lokke Rasmussen accused Russia of “gradually shifting the boundary for what they consider acceptable behaviour”, adding: “That is something we cannot accept.”

Overnight, Nato fighter pilots shot down a drone that entered Lithuania’s airspace.

Authorities said the drone likely entered southern Lithuania, near the second-largest city of Kaunas, from neighbouring Belarus shortly after midnight on Tuesday.

The origins of the drone are yet to be determined, the Lithuanian national crisis management centre said, but the country’s president pointed to increased Russian aggression in recent months.

President Gitanas Nausėda wrote on X: “With Russia intensifying its aggression against Ukraine, such readiness is vital for our region. Together with our Nato Allies, Lithuania will defend its airspace.”

Lithuania shares a large part of its southern and eastern border with Belarus, a key Russian ally.

Poland also announced there had been “aviation operations” in its airspace on Monday night “due to the activity of Russian Federation’s jet-powered unmanned aerial vehicles conducting strikes on Ukrainian territory”.

It said the overnight operations were of a “preventive nature” and aimed at “securing airspace and its protection, especially in areas adjacent to threatened regions”.

Nato jets have been scrambled several times to shoot down stray Ukrainian drones that have crossed into Baltic countries Estonia and Latvia this year.

Ukraine has blamed the stray drones on Russian electronic warfare, technology designed to change the flight paths of Ukrainian drones.