"Russian ambassador has just received a protest against the grave violation of Swedish airspace by Russian fighters-bombers on Wednesday," outgoing Foreign Minister Carl Bildt tweeted on Friday afternoon.
Bildt also published a blog entry, writing, "I can add that this concerns the most serious air violation from the Russian side that has taken place during the years that I've been Foreign Minister. Earlier incidents of this sort have hardly been of a serious nature," adding, "This is."
Earlier in the day, the press secretary for the minister had told Swedish Radio News that they had asked for an emergency report from the Armed Forces about the incident for evaluation.
The Swedish Armed Forces confirmed on their website that two Russian SU-24 planes had violated Swedish airpace for about 30 seconds around lunchtime on Wednesday, and that they had come a kilometer in over Swedish territory. According to TT, Gabor Nagy, the head of flight tactics at the Swedish Armed Forces headquarters, said the planes had come from Kaliningrad, and are attack and reconnaissance planes. He said it was unlikely that this incident was a mistake, because the planes are well-equipped to define their positions.
"Obviously, we knew where the Russian planes were, first with radar, and then with a Swedish pursuit plane that was in the area on another assignment," Nagy is quoted as saying on the Armed Forces website. "Moreover, a quick reaction alert was sent up and identified the Russian planes," he added.
In October 2013 five Russian planes practised bombing attacks against Sweden, Poland and the Baltic States. Sweden was able to have two planes in the vicinity.
On Good Friday two Russian planes also practised near Sweden. Gripen fighters were not able to counter this symbolic gesture, something that caused sharp criticism of Sweden's readiness to meet threats from the air.
Despite the ending of the Cold War Swedish airspace is still in the middle of a face-off between Russian and Nato airforces.
On July 18 a US reconnaissance plane flew over Sweden, after being chased from international airspace by Russian fighters.
On June 20 two Polish (Nato) planes flew over Sweden, probably by mistake, according to Carl Bildt.