"We have confirmed through the Swedish defence ministry that the aircraft was Russian," Johannes Hellqvist, a spokesman for the Swedish defence forces, told AFP.

The incident happened amid growing concern in the Baltic region over signs of a more assertive Russian behaviour, including Russian planes skirting or violating the national air space near Denmark, including a simulated attack on Bornholm and a previous near-miss with an SAS flight on March 3rd. In that instance, a SAS flight carrying 132 passengers was just 90 metres from colliding with a Russian surveillance aircraft.

 

Concerns are fuelled by the role Russian has been playing the Ukrainian crisis, including the annexation of Crimea.

 

Both Swedish and Danish jet fighters were scrambled in response to the incident Friday, Hellqvist said.

 

The Russian plane never actually violated Swedish air space, Sweden's Defence Minister Peter Hultqvist was quoted by Swedish news agency TT as saying.

 

Hultqvist said the Russian airplane had been flying without a transponder – an electronic identification device that would have made it visible on the radar of the commercial plane.

 

He described it as "irresponsible" for Russian planes to frequently fly without transponders.

 

"There is a risk that accidents could occur that could ultimately lead to deaths," he said according to TT.

 

The passenger plane was not immediately identified. According to Politiken, it was on the way to Poland.

 

Poland's defence minister, Tomasz Siemoniak, warned Thursday that in recent days there had been "unprecedented Russian activity from its Baltic fleet to flights over the Baltic Sea", and on Friday his coounterpart in Estonia said a Russian plane had violated its airspace.